Class 9

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 13 Carbon: An Important Element Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 13 Carbon: An Important Element

Class 9 Science Chapter 13 Carbon: An Important Element Textbook Questions and Answers

1. Select the proper option and complete the statements
(single, all, double, ionic, carbon, give and take, hydrogen, multiple, share, most, covalent)

a. A carbon atom forms a ….……………. bond with other atoms. In this bond the two atoms ….electrons.
Answer:
covalent, share

b. All the carbon bonds in a saturated hydrocarbon ….……………. electrons.
Answer:
share

c. At least one carbon bond in an unsaturated hydrocarbon is ….…………… .
Answer:
multiple

d. ….……………. is the essential element in all the organic compounds.
Answer:
Carbon

e. The element hydrogen is present in ….. organic compound.
Answer:
all

2. Answer the following questions

a. Why are carbon and its compounds used as fuels?

Answer:
(i) The name ‘carbon’ is derived from Latin word ‘carbo’meaning coal. In the earth’s crust, carbon is present to an extent of approximately 0.27% in the form of carbonate, coal and petroleum. One of the non-crystalline and amorphous form of carbon is coal. Coal is a fossil fuel.

(ii) Peat, lignite, bituminous and anthracite are the four types of coal in the increasing order of their carbon content and heat produced respectively. Charcoal and coke are the other amorphous forms of carbon used as fuel.

(iii) Compounds of carbon such as hydrocarbons consist of carbon and hydrogen and they are easily combustible. For example, methane (CH₄) which occurs in natural gas is highly inflammable. It bums by reacting with oxygen to give a bluish flame. In this reaction, 213 Kcal/mol of heat is given out. Methane bums completely.

Chemical reaction:
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat

(iv) Thus when hydrocarbons are burnt in air, large amount of heat is evolved with formation of carbon dioxide (CO₂) and water (H₂O). Due to evolution of heat on combustion, carbon and its compounds are used as fuels.

b. In which compound forms does carbon occur?
Answer:
Carbon in its combined state exists as various compounds such as:

• Carbon dioxide and in the form of carbonates such as calcium carbonate, marble, calamine (ZnCO₃).
• Fossil fuel – coal, petroleum, natural gas.
• Carbonaceous nutrients – carbohydrates, proteins, fats.
• Natural fibres – cotton, wool, silk.
• Hydrocarbons – compound of carbon and hydrogen.

c. Write the uses of the diamond.
Answer:
Uses of diamonds are:

• Diamonds are used in glass cutting and rock drilling machines.
• Diamonds are used in ornaments.
• Diamond knives are used in the eye surgery.
• Diamond dust is used for polishing other diamonds.
• Diamond is used to make windows giving protection from radiation in space and in artificial satellites.

3. Explain the difference:

a. Diamond and graphite.

Answer:

Diamond	Graphite
(i) Diamond is a brilliant, hard and crystalline allotrope of carbon.	(i) Graphite is a black, soft, brittle and slippery crystalline allotrope of carbon.
(ii) In diamonds, every carbon atom is bonded to four neighbouring atoms by covalent bonds forming tetragonal three dimensional structure which makes it very hard.	(ii) In graphite, every carbon atom is bonded to three other carbon atoms by covalent bonds in such a way that a hexagonal layered structure is formed. A graphite crystal is made of many such layers of carbon atoms. These layers slip over each other on applying pressure.
(iii) Density of diamond is 3.5 g/cm3.	(iii) Density of graphite is 1.9 to 2.3 g/cm3.
(iv) Diamond is a bad conductor of electricity as it does not have free electrons.	(iv) Inside each layer of graphite, free electrons move continuously within the entire layer. Hence, graphite is a good conductor of electricity.

b. Crystalline and non-crystalline forms of carbon.
Answer:

Crystalline forms of carbon	Non-crystalline forms of carbon
(i) A crystalline form has a regular and definite arrangement of atoms. (ii) They have high melting points and boiling points. (iii) A crystalline form has a definite geometrical shape, sharp edges and plane surfaces. (iv) Diamond, graphite and fullerene are different crystalline forms of carbon.	(i) A non-crystalline form does not have a regular and definite arrangement of atoms. (ii) They have low melting points and boiling points. (iii) They are amorphous, hence, they do not have definite geometrical shape. (iv) Coal, charcoal and coke are different non­crystalline/amorphous forms of carbon.

4. Write scientific reasons

a. Graphite is a conductor of electricity.
Answer:

• In graphite, each carbon is bonded to three other carbon atoms in such a way that a hexagonal layered structure is formed.
• Due to this structure, graphite has free electrons available.
• These free electrons move continuously within the entire layer.
• Hence, graphite is a good conductor of electricity.

b. Graphite is not used in ornaments.
Answer:

• Graphite is a black, soft, brittle and dull form of carbon.
• It is neither malleable nor ductile.
• These properties of graphite make it unsuitable for making of ornaments.
• Hence, graphite is not used for making ornaments.

c. Limewater turns milky when CO₂ is passed through it.
Answer:

• Limewater traditionally means a weak solution of the alkali calcium hydroxide Ca(OH)₂.
• When CO₂ is passed through limewater, it reacts with calcium hydroxide to form insoluble particulates (precipitate) of Calcium carbonate (CaCO₃).
• Calcium carbonate is weak basic salt and this gives a milky white precipitate.
• Hence, lime water turns milky when CO₂ gas is passed through it.

d. Biogas is an eco-friendly fuel.
Answer:

• Biogas is formed by the decomposition of animal dung, dry leaves, wet garbage in a biogas plant.
• This produces methane gas also called biogas.
• Biogas is a very cheap fuel option which meets the demand for cooking gas.
• Biogas is eco-friendly as it contains about 55% to 60% of methane and rest is carbon dioxide, hence, on combustion it does not produce harmful gases which cause pollution.
• Biogas is a fuel which is convenient to use and in addition to this it produces a very good manure as a side product of the process.
• Hence, biogas is an eco-friendly fuel.

5. Explain the following.

a. Diamond, graphite and fullerenes are crystalline forms of carbon.
Answer:

• Carbon exhibits a property of allotropy in which an element exists in more than one form in nature.
• The chemical properties of these different forms are the same but their physical properties are different.
• Carbon exists in crystalline as well as non-crystalline (amorphous form).
• Crystalline form has a regular and definite arrangement of atoms. They have high melting points and boiling points.
• A crystalline form has a definite geometrical shape, sharp edges and plane surfaces.
• Carbon has three crystalline allotropes such as diamond, graphite and fullerene.
• In the structure of diamond, every carbon atom is bonded to four neighbouring atoms by covalent bonds.
• Therefore, diamond has a tetragonal three dimensional structure which makes it very hard.
• Brilliant and pure diamond is the hardest natural substance.
•  In the structure of graphite, every carbon atom in graphite is bonded to three other carbon atoms in such a way that a hexagonal layered structure is formed.
• A graphite crystal is made of many sheets or layers of carbon atoms.
• These layers slip over each other on applying pressure. One layer of graphite is called graphene.
• Fullerene is rarely found in nature. It is found in soot and in interstellar space.
• The first example of fullerene is Buckminster fullerene (C₆₀).
• This allotrope of carbon is named fullerene after the architect.
• Richard Buckminster Fuller because the structure of C₆₀ resembles the structure of the geodesic dome he designed.
• (xi) Molecules of fullerenes are found in the form of buckyballs and buckytubes.
• (xii) There are 30 to 900 carbon atoms in one molecule of a fullerene. , C₆₀, C₇₀, C₇₆, C₈₂ and C₈₆ are other examples of fullerene. Their molecules occur in small numbers in soot.

b. Methane is called marsh gas.
Answer:

• Methane is formed by the decomposition of plant and animal matter in swamps or marshy areas.
• As methane gas bubbles out from marshy area, it is called as marsh gas.

c. Petrol, diesel, coal are fossil fuels.
Answer:
(i) A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms. Fossil fuels contain high percentage of carbon. The word carbon is derived from the Latin word ‘Carbo’ meaning coal.

(ii) Coal is formed from the remains of trees and other vegetation. Approximately 350 million years ago, these remains were trapped on the bottom of swamps, accumulating layer after layer and creating a dense material called peat. As this peat was buried under more and more ground, the high temperature and pressure transformed it into coal.

(iii) Petrol and diesel are obtained from mineral oil. Mineral oil also called as crude oil or petroleum oil is formed from the remains of plants and animals that lived in the seas millions of years ago. This plant and animal matter has been drawn down and subjected to extremes of temperature and pressure over millions of years ago.

(iv) Mineral oil is commonly formed in rocks under the sea bed. The word petroleum is derived from Latin word ‘Rock oil’. Petrol and Diesel are obtained from mineral oil by the process called as fractional distillation.
Thus petrol, diesel and coal are fossil fuels.

d. Uses of various allotropes of carbon.

e. Use of CO₂ in fire extinguisher.
Answer:

• CO₂ based fire extinguishers do not cause corrosion and are non-conductors of electricity.
• It is beyond their capacity to extinguish a big fire.
• Therefore these fire extinguishers are used to extinguish small scale fire of electrical and electronic equipments.

f. Practical uses of CO₂.
Answer:
Practical uses of CO₂ are:

• CO₂ is used to make aerated drinks.
• CO₂ obtained by chemical reaction or kept under pressure is used in fire extinguishers. Liquified CO₂ is used to remove caffeine from coffee.
• Liquid CO₂ is used as solvent in modem eco-friendly dry cleaning.
• Solid carbon dioxide is used in cold storage and to keep milk and milk products and frozen substances cool during transport. It is also used for getting special effects of a mist in dramas and movies.

6. Write two physical properties each.

a. Diamond
Answer:
Properties of diamond are:

• Brilliant and pure diamond is the hardest natural substance.
• The density of diamond is 3.5 g/cm³.
• The melting point of diamond is 3500 °C.
• When a diamond is heated at 800 °C in the presence of oxygen, CO₂ is given away. In this process no other product besides CO₂ is formed.
• Diamond does not dissolve in any solvent.
• Acids/bases have no effect on diamond.
• Diamond is a bad conductor of electricity as it does not have free electrons.

b. Charcoal
Answer:

• The charcoal that is made from animals is made from their bones, horns, etc.
• On the other hand, the charcoal made from plants is formed by combustion of wood in an insufficient supply of air.

c. Fullerene
Answer:
Properties of fullerenes are:

• Molecules of fullerenes are found in the form of buckyballs and buckytubes.
• There are 30 to 900 carbon atoms in one molecule of a fullerene.
• Fullerenes are soluble in organic solvents such as carbon disulphide, chlorobenzene.

7. Complete the following Chemical reactions.

1. ………………..+………………..→ CO + 2H₂O + Heat
2. ………………..+………………..→ HCl + Cl + HCl
3. 2 NaOH + CO₂ →………………..+………………..
Answer:

8. Write answers to the following in detail.

a. What are the different types of coal? What are their uses?
Answer:
Coal is a fossil fuel. It contains carbon, hydrogen and oxygen. It also contains nitrogen, phosphorus and sulphur. It occurs in the solid state. It is of four types.

• Peat: Formation of peat is the first step in the formation of coal. It contains a high proportion
  of water and less than 60% of carbon. Therefore, not much heat can be obtained from peat.
• Lignite: Peat was transformed into Lignite due to increased pressure and temperature inside the earth. It contains 60 to 70% of carbon.- Lignite is the second step of the formation of coal.
• Bituminous coal: Bituminous coal was formed as the third step of formation of coal. It contains 70 to 90% of carbon.
• Anthracite: Anthracite is known as the pure form of coal. This coal is hard and contains about 95% of carbon.

Uses of coal:

• Coal is used as fuel in factories and homes.
• Coal is used to obtain coke, coal gas and coal tar.
• Coal is used in thermal power plants for generation of electricity.

b. How will you prove experimentally that graphite is good conductor of electricity?
Answer:
Apparatus required: Lead pendi, electrical wires, battery/cell, small bulb, etc.

Step-I: Remove the lead from a pencil and assemble the apparatus as shown in the diagram.

Step-II:

• Start the electric current in the circuit, the moment the electric current is passed through the circuit, the bulb glows.
• This experiment proves that graphite is a good conductor of electricity as graphite has free electrons moving continuously within the entire layer and these free electrons conduct electricity in the lead of the pencil.

c. Explain the properties of carbon.
Answer:
Allotropic nature of Carbon: Some elements occur in nature in more than one form. The chemical properties of these different forms are the same but their physical properties are different. This property of elements is called allotropy. Carbon shows the property of allotropy.

Carbon allotropes are of two types:
(A) Crystalline forms:
Carbon has three crystalline allotropes: Diamond, Graphite and Fullerene. Properties of crystalline forms of carbon are as follows:

• A crystalline form has a regular and definite arrangement of atoms.
• They are made up of only carbon atoms.
• They have high melting points and boiling points.
• A crystalline form has a definite geometrical shape, sharp edges and plane surfaces.

(B) Amorphous forms or non-crystalline forms: Coal, charcoal, coke are the non-crystalline forms of carbon.
Properties of non-crystalline forms of carbon are as follows:

• The arrangement of carbon atoms in this form is not regular.
• Apart from carbon atoms, they also contain hydrogen, oxygen, nitrogen, phosphorus and sulfur atoms.
• Compared to a crystalline form, they have low melting and boiling points.
• Most of them are used as fuels.

d. Classify carbon.
Answer:
Carbon is classified as follows:

9. How will you verify the properties of carbon dioxide?
Answer:
Properties of carbon dioxide can be verified in the following ways:

• When a burning candle is placed in a gas jar of carbon dioxide, it extinguishes indicating that carbon dioxide is a non-combustible gas and does not support combustion.
• When carbon dioxide gas is passed through lime water, it turns lime water milky due to the formation of insoluble calcium carbonate.
• Moist blue litmus turns red in a gas jar of carbon dioxide indicating, it is acidic in nature.
• Carbon dioxide is fairly soluble in water, it dissolves in water forming carbonic acid.

Class 9 Science Chapter 13 Carbon: An Important Element Intext Questions and Answers

Can you recall?

Question 1.
Whatremains behind on complete combustion of any organic compound?
Answer:
A black colour substance ‘Carbon’ remains behind on complete combustion of any organic compound.

Question 2.
What type of element is carbon? Give some information about it.
Answer:

• Carbon is a non-metallic element. It is available ‘ abundantly in the nature and occurs in free as well as combined state.
• Carbon in free state is found as diamond and graphite and in combined state it is present to the extent of approximately 0.27% in the form of carbonate, coal, petroleum.
• In atmosphere, the proportion of carbon in the form of carbon dioxide is approximately 0.03%.

Question 3.
What is an element? What are the different types of elements.
Answer:

• A substance which cannot be decomposed into simple substances by any physical or simple chemical method is called as an Element.
• An element is composed of atoms of only one kind.
• The different types of elements are:
  (a) Metals – Examples: Gold, Silver, etc.
  (b) Non-metals – Examples: Carbon, Sulphur, etc.
  (c) Metalloids – Examples: Silicon, Antimony, etc.

Answer the following questions:

Question 1.
Does an electric charge form on atoms when a covalent bond is formed between them? Why is a single bond between two carbon atoms strong and stable?
Answer:

• No, electric charge is not formed on atoms when a covalent bond is formed between them. This is because covalent bond is formed by sharing of electrons.
• Therefore, there is no change in number of electrons and protons in these atoms and they remain electrically neutral.
• Covalent bonds occur when electrons are shared between two atoms. A single covalent bond is formed when only one pair of electrons is shared between atoms.
• In this sharing, the atomic orbitals directly overlap between the nuclei of two atoms forming the strongest type of covalent bond called as sigma bond.
• Hence, a single covalent bond between two carbon atoms is strong and stable.

Question 2.
In which of the solvents – water, kerosene and cooking oil does the coal powder dissolve?
Answer:
Solvents such as water, kerosene and cooking oil do not dissolve coal powder in them.

Question 3.
What inference will you draw about the solubility of carbon?
Answer:
Carbon is insoluble in water, kerosene and cooking oil.

Question 4.
Is the density of CO₂ more or less than that of air?
Answer:

1. Density is defined as mass per unit volume of a substance, expressed as kilograms per cubic meter.
2. At standard temperature and pressure, the density of air is 1.29 kg/m³. While that of carbon dioxide (CO₂) is 1.79 kg/m³. Hence, density of CO₂ is more than that of air.

Question 5.
What is a compound? How are compounds formed?
Answer:

• A compound is a substance formed when two or more elements are chemically bonded with each other in definite proportion by weight.
• When atoms or two or more different elements chemically react with each other in a definite proportion by weight, a compound is formed.
• The properties of a compound are altogether different from its constituent elements.
• Example: Pure water is a compound made up of two elements Hydrogen and Oxygen. Hydrogen (H) atoms and oxygen (O) atoms have chemically reacted with each other in definite proportion to form a compound-water (H₂O). The proportion of hydrogen and oxygen in water by volume is 2 : 1 and by weight is 1 :8 respectively.
• The properties of water are altogether different from the properties of its constituent elements, hydrogen and oxygen.

Class 9 Science Chapter 13 Carbon: An Important Element Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
The organic compound having double or triple bond in them is termed as
(a) unsaturated
(b) inorganic
(c) saturated
(d) complete
Answer:
(a) Unsaturated hydrocarbon

Question 2.
Covalent compounds are generally soluble in solvents.
(a) inorganic
(b) organic
(c) mixed
(d) mineral
Answer:
(b) organic

Question 3.
Methane is also called as
(a) maha gas
(b) mar’s gas
(c) Anthracite
(d) marsh gas
Answer:
(d) Marsh gas

Question 4.
is an alio trope of carbon used to make ornaments.
Answer:
Diamond

Question 5.
The number of valence electrons in carbon is
(a) 4
(b) 5
(c) 6
(d) 3
Answer:
(a) 4

Question 6.
In saturated hydrocarbons, two carbon atoms are linked by
(a) double bond
(b) triple bond
(c) multiple bond
(d) single bond
Answer:
(d) single bond

Question 7.
Carbon has 4 valence electrons in its outermost shell, hence, it is
(a) divalent
(b) tetravalent
(c) trivalent
(d) pentavalent
Answer:
(b) tetravalent

Question 8.
Methanogenic bacteria act on the organic acids to produce
(a) oxygen gas
(b) nitrogen gas
(c) methane gas
(d) carbon dioxide gas
Answer:
(c) Methane gas

Question 9.
is used to remove caffeine from coffee.
(a) liquefied O₂
(b) liquefied N₂
(c) liquefied CO₂
(d) liquefied CH₄
Answer:
(c) Liquified CO₂

Question 10.
Exhaled air contains about CO₂.
(a) 4%
(b) 3%
(c) 5%
(d) 6%
Answer:
(a) 4%

Question 11.
Electronic configuration of carbon is
(a) (2, 2)
(b) (2,4)
(c) (2, 5,4)
(d) (2, 6)
Answer:
(b) 2, 4

Question 12.
Molecular formula of ethane is
(a) C₃H₄
(b) C₂H₄
(c) C₂H₆
(d) C₂H₂
Answer:
(c) C₂H₆

Question 13.
Molecular mass of carbon dioxide is
(a) 28
(b) 22
(c) 56
(d) 44
Answer:
(d) 44

Question 14.
On heating a mixture of hydrogen and carbon monoxide gases at 300°C in the presence of nickel (catalyst) is formed.
(a) carbon dioxide gas
(b) oxygen gas
(c) methane gas
(d) ethylene gas
Answer:
(c) methane gas

Question 15.
Ethane with molecular formula C₂H₆ has covalent bonds.
(a) six
(b) seven
(c) eight
(d) nine
Answer:
(b) seven

Question 15.
Weight of Kohinoor Diamond was
(a) 186 carats
(b) 27 carats
(c) 252 carats
(d) 23 carats
Answer:
(a) 186 carats

Question 16.
Covalent compounds have
(a) high melting point
(b) low melting point
(c) moderate melting point
(d) very high melting point
Answer:
(b) low melting point

Question 17.
Methane is
(a) C₂H₆
(b) C₃H₈
(C) CH₂
(d) CH₄
Answer:
(d) CH₄

Question 18.
Wohler, a German scientist synthesized the compound from an inorganic compound ammonium cyanate.
(a) methane
(b) ethylene
(c) urea
(d) acetic acid
Answer:
(c) urea

Question 19.
Molecular mass of methane is
(a) 19
(b) 16
(c) 17
(d) 18
Answer:
(b) 16

Question 20.
coal contains highest percentage of carbon.
(a) Bituminous
(b) Peat
(c) Anthracite
(d) Lignite
Answer:
(c) Anthracite

Question 21.
H₂C = CH₂ is ……………………… .
(a) Propane
(b) Ethyne
(c) Ethane
(d) Ethene
Answer:
(d) Ethene

Question 22.
CH₃ – C = CH is ……………………… .
(a) Propene
(b) Propyne
(c) Ethyne
(d) Ethene
Answer:
(b) Propyne

Question 23.
Carbon dioxide gas is not used in
(a) photosynthesis
(b) aerated drinks
(c) glass cutting
(d) fire extinguishers
Answer:
(c) glass cutting

Question 24.
Melting point of diamond is
(a) 3700 °C
(b) 3500 °C
(c) 4000 °C
(d) 2500 °C
Answer:
(b) 3500 °C

Question 25.
Melting point of C02 is
(a) 26 °C
(b) 56 °C
(c)-56.6°C
(d)-98°C
Answer:
(c) -56.6 °C

Question 26.
Melting point o* methane is
(a) -182.5 °C
(b) -161.5 °C
(c) 182.5 °C
(d) 161.5 °C
Answer:
(a) -182.5 °C

Question 27.
Biogas contains about methane.
(a) 55% to 60%
(b) 20% to 25%
(c) 90% to 95%
(d) 40% to 45%
Answer:
(a) 55% to 60%

Question 28.
is not a property of carbon dioxide gas.
(a) Supporting combustion
(b) Odourless
(c) Colourless
(d) Turns blue litmus red
Answer:
(a) Supporting combustion

Name the following:

Question 1.
Industries that use methane in the form of natural gas.
Answer:
Fabric mills, paper mills, food processing industry, petrol purification.

Question 2.
Organic compounds prepared from methane.
Answer:
Ethanol, methyl chloride, methylene chloride, acetylene.

Question 3.
Chemicals used in regular fire extinguisher.
Answer:
Sodium bicarbonate and dilute sulphuric acid.

Question 4.
Components of biogas
Answer:
Methane, carbon dioxide

Question 5.
Organic solvents is which fullerenes are soluble.
Answer:
Carbon disulfide, chlorobenzene.

Question 6.
Use of carbon dioxide is dramas and movies
Answer:
The special effect of mist.

Match the columns:

Question 1.

Column ‘A’	Column ‘B’
(1) Diamond (2) Fullerenes (3) Graphite	(a) Hexagonal layered structure (b) Tetragonal three-dimensional structure (c) Geodesic dome

Answer:
(1-b),
(2- c),
(3 – a)

Question 2.

Column ‘A’	Column ‘B’
(1) Peat (2) Lignite (3) Bituminous (4) Anthracite	(a) 60-70% of Carbon (b) 95% of Carbon (c) less than 60% of Carbon (d) 70 – 90% of Carbon

Answer:
(1 – c),
(2 – a),
(3 – d),
(4 – b)

Question 3.

Column ‘A’	Column ‘B’
(1) Propyne (2) Propene (3) Propane	(a) CH3 – CH2 – CH3 (b) CH3 – C = CH (c) CH3 – CH = CH2

Answer:
(1 – b),
(2 – c),
(3 – a)

Question 4.

Column ‘A’	Column ‘B’
(1) Fullerene (2) Diamond (3) Graphite	(a) Lubricants (b) Insulator (c) Ornaments

Answer:
(1 – b),
(2 – c),
(3 – a)

Question 5.

Column ‘A	Column ‘B’
(1) Water gas (2) Methane gas (3) Producer gas (4) Carbon dioxide gas	(a) CH4 (b) CO + H2 (c) CO2 (d) CO + H2 + CO2 + N2

Answer:
(1 – b),
(2 – a),
(3 – d),
(4 – c)

State whether the following statements are true or false. Correct the false statement.

(1) Study of organic compounds is called as organic chemistry.
(2) Hydrocarbons with double bonds are called as saturated hydrocarbons.
(3) Ethene is saturated hydrocarbon.
(4) Covalent compounds are good conductor of electricity.
(5) Methane is a covalent compound.
(6) Covalent compounds are soluble in organic solvents.
(7) Graphite is used in making lubricants and lead pencils.
(8) The density of diamond is 9.8 g/cm³.
(9) Diamond knives are used in eye surgery.
(10) Fullerenes are used as insulators.
(11) Coke is used in production of water gas i.e. (CO₂ + H₂O).
(12) Structural formula of propyne is CH₃ – C = CH.
(13) COz is used to make aerated drinks.
(14) Methane gas is black in colour.
(15) Production of biogas is aerobic process.
Answer:
(1) True
(2) False. Hydrocarbons with double bonds are called as Unsaturated hydrocarbons.
(3) False. Ethene is Unsaturated hydrocarbon.
(4) False. Covalent compounds are bad conductor of electricity.
(5) True
(6) True
(7) True
(8) False: The density of diamond is 3.5 g/cm³.
(9) True
(10) True
(11) False. Coke is used in production of water gas i.e. (CO + H₂).
(12) False. Structural formula of propyne is CH₃ – C = CH.
(13) True
(14) False. Methane gas is colourless.
(15) False. Production of biogas is anaerobic process.

Find the odd man out:

Question 1.
Propane, Methane, Ethene, Pentane.
Answer:
Ethene. It is an unsaturated hydrocarbon with double bond between two carbon atoms while rest are saturated hydrocarbons with single bond between two carbon atoms.

Question 2.
CH₄, C₂H₆, C₃H₈, CaCO₃.
Answer:
CaCO₃. It is a salt which is an inorganic’ compound, while rest are hydrocarbon compounds, i.e. organic compounds.

Question 3.
C₂H₂, C₃H₈, C₂H₆, CH₄.
Answer:
C₂H₂. It is an unsaturated hydrocarbon with triple bonds while rest are saturated hydrocarbons with single bonds between two carbon atoms.

Question 4.
Diamond, Fullerene, Graphite, Methane.
Answer:
Methane. It is a marsh gas while rest are allotropes of carbon.

Question 5.
Coal, Petroleum, Natural gas, Cotton
Answer:
Cotton. Cotton is a natural fibre while rest all are fossil fuels.

Question 6.
Cotton, Silk, Proteins, Wool
Answer:
Proteins. Proteins are carbonaceous nutrients while rest all are natural fibres.

Question 7.
Carbohydrates, Coal, Proteins, Fats
Answer:
Coal. Coal is a fossil fuel while rest all are carbonaceous nutrients.

Question 8.
Peat, Charcoal, Lignite, Bituminous
Answer:
Charcoal. Charcoal is a non-crystalline form of carbon while rest all are types of coal.

Question 9.
Lubricants, Electrodes, Ornaments, Arc Lamps
Answer:
Ornaments. Ornaments are made from diamonds while rest all are made from graphite.

Write the correlated terms:

(1) Propene : Double bond :: Propyne : ……………………. .
(2) Ethane : CH₃ – CH₃ :: Ethene : ……………………. .
(3) Hydrogen : Monovalent :: Carbon : ……………………. .
(4) Methane : Low melting point i.e. -182.5°C Diamond : ……………………. .
(5) Graphite : Hexagonal structure :: Diamond : ……………………. .
(6) Density of Diamond : 3.5 g/cm³ :: Density of Graphite : ……………………. .
(7) Peat: 60% of carbon :: Anthracite : ……………………. .
(8) Melting point of CO₂: -56.6°C :: Melting point of CH₄: ……………………. .
Answer:
(1) Triple Bond
(2) CH₂ = CH₂
(3) Tetravalent
(4) High melting point i.e. 3500°C
(5) Tetragonal structure
(6) 1.9 to 2.3 g/cm³
(7) 95% of carbon
(8) -182.5 °C

Give scientific reasons:

Question 1.
Covalent compounds have low melting and boiling points.
Answer:

• When substances melt or boil, bonds between the molecules are broken due to heat supplied.
• On covalent compounds, the intermolecular forces of attraction are weak.
• Hence, intermolecular forces in covalent compounds are broken easily due to which they have low melting and boiling points.

Question 2.
Graphite is a good conductor of electricity whereas diamond is a non-conductor of electricity.
Answer:

• In diamond, each carbon atom uses all its four electronic to get bonded to another carbon atom, whereas in graphite each carbon uses there out of four electrons during bonding.
• Hence in diamond no free electrons are left whereas in graphite free electrons are available.
• Due to the presence of electron which are free to flow graphite is a good conductor of electricity, whereas due to the absence of free electrons diamond is a non-conductor of electricity.

Question 3.
Graphite is used as a lubricant.
Answer:

• Lubricants are used to reduce friction and wear and tear of mechanical parts.
• Graphite is smooth and slippery and hence is useful in reducing friction. Hence, graphite is used as a lubricant.

Question 4.
Methane is used as a domestic fuel.
Answer:

• Methane is highly inflammable.
• It burns by reacting with oxygen to give a bluish flame.
• It burns completely and producers 213 Kcal/ mol of heat.
• Being the smallest hydrocarbon, the proportion of CO2 released in the combustion of methane is small.
• Therefore methane is used as a domestic fuel.

Answer in short:

Question 1.
What was the contribution of chemist Wohier in organic chemistry?
Answer:

• The German chemist Wohier synthesized an organic compound urca from an inorganic compound ammonium cyanate,
• Ever since then, many organic compounds have been made from inorganic compounds.
• Carbon was found to he the main element in all these compounds.
• Hence, organic chemistry is also referred to as chem is try of carbon corn pounds.

Question 2.
With neat diagram explain the structure of diamond.
Ans.

• In diamond, every carbon atom is bonded to four neighbouring atoms by covalent bonds.
• Therefore, diamond has a tetragonal three dimensional structure which makes it very hard.
  

Question 3.
With neat diagram explain the structure of graphite?
Answer:

• Every carbon atom in graphite is bonded to three other carbon atoms in such a way that a hexagonal layered structure is formed.
• A graphite crystal is made of many sheets or layers of carbon atoms.
• These layers slip over each other on applying pressure.
• One layer of graphite is called graphene.
  

Question 4.
Give the properties of graphite.
Answer:
Properties of graphite are:

• Graphite found in nature is black, soft, brittle and slippery.
• Inside each layer of graphite, free electrons move continuously within the entire layer. That is why graphite is a good conductor of electricity.
• Due to the layered structure graphite can be used for writing on paper.
• The density of graphite is 1.9 to 2.3 g/cm3.
• Graphite does not dissolve in most solvents.

Question 5.
Give the uses of graphite.
Answer:
Uses of graphite are:

• Graphite is used for making lubricants.
• Graphite is used for making carbon electrodes.
• Graphite is used in pencils for writing.
• Graphite is used in paints and polish.
• Graphite is used in arc lamps which gives a very bright light.

Question 6.
Give the uses of fullerenes.
Answer:
Uses of Fullerenes are:

• Fullerenes are used as insulators.
• Fullerenes are used as a catalyst in water purification.
• At a certain temperature, fullerene exhibits superconductivity.

Question 7.
What is Coal?
Answer:

• Coal is a fossil fuel. It contains carbon, hydrogen and oxygen.
• It also contains nitrogen, phosphorus and sulphur.
• It occurs in the solid state. It is of four types – peat, lignite, bituminous and anthracite.

Question 8.
What is Coke?
Answer:
The pure coal that remains when coal gas has been taken away from coal, is called coke.

Question 9.
Give the uses of Coal.
Answer:
Uses of Coal are:

• Coal is used as fuel in factories and homes.
• Coal is used to obtain coke, coal gas and coal tar.
• Coal is used in thermal power plants for generation of electricity.

Question 10.
Give the uses of Coke.
Answer:
Uses of Coke are:

• Used as domestic fuel.
• Coke is used as a reducing agent.
• Coke is used in production of water gas (CO + H₂) and producer gas (CO + H₂ + CO₂ + N₂)

Question 11.
Name the types of coal and give the differences in them.
Answer:
The four types of coal are Peat, Lignite, Bituminous and Anthracite.

Question 12.
Give the properties of covalent compounds.
Answer:
Properties of covalent compounds:

• Covalent compounds have low melting points and boiling points.
• Generally they are insoluble in water and soluble in organic solvents.
• They are poor conductors of heat and electricity.

Question 13.
What are saturated hydrocarbons? Give examples.
Answer:

• The hydrocarbons having only single bonds between carbon atoms are called saturated hydrocarbons.
• For example, ethane (C₂H₆) which is (CH₃ – CH₃), propane (C₃H₈) which is (CH₃ – CH₂ – CH₃).

Question 14.
What are unsaturated hydrocarbons? Give examples.
Answer:

• Some hydrocarbons have a multiple bond between two carbon atoms.
• A multiple bond can be a double bond or a triple bond.
• Hydrocarbons having at least one multiple bond are called unsaturated hydrocarbons.
• For example, ethene (H₂C = CH₂), ethyne (HC = CH), propene (CH₃ – CH = CH₂), propyne (CH₃ – C = CH).

Question 15.
Give the following information of carbon dioxide: Molecular formula, Molecular mass, Melting point, Percentage occurrence in air.
Answer:
Molecular formula – CO₂, Molecular mass – 44, Melting point -56.6 °C Percentage occurrence in air – 0.03%.

Question 16.
Give the physical and chemical properties of carbon dioxide.
Answer:
Physical properties of carbon dioxide are:

• It is an odourless gas.
• It is a colourless gas.

Chemical properties of carbon dioxide are:

• It is non-combustible and does not support combustion.
• It turns lime water milky.
• It is fairly soluble in water and dissolves in water forming carbonic acid.
• It turns blue litmus red indicating it is acidic in nature.
• The colour of universal indicator turns orange/ yellow in C02 indicating its pH value between 4 and 6, i.e. acidic in nature.

Question 17.
Give the uses of Carbon dioxide.
Answer:
Uses of Carbon dioxide are:

• CO₂ is used to make aerated drinks
• Solid carbon dioxide is used in cold storage and also to keep milk and milk products and frozen substances cool during transport. It is also used for getting special effects of a mist in dramas and movies.
• CO₂ obtained by chemical reaction or kept under pressure is used in fire extinguishers.
• Liquified CO₂ is used to remove caffeine from coffee.
• Liquid CO₂ is used as solvent in modern eco-friendly dry cleaning.
• Plants use CO₂ in air for photosynthesis.

Question 18.
Give the occurrence of methane.
Answer:
The occurrence of methane is as follows:

• Methane occurs in natural gas to the extent of 87%.
• Decomposition of organic matter in the absence of air (anaerobic) produces methane.
• Methane is present in biogas.
• Methane is found in coal mines.
• Methane is found at the surface of marshy places which is why it is also called marsh gas.
• On heating a mixture of hydrogen and carbon monoxide gases at 300 °C in the presence of nickel (catalyst), methane gas is formed.
• Fractional distillation of natural gas gives methane in pure form.

Question 19.
Give the physical properties of methane.
Answer:
Physical properties of methane are:

• Melting point of methane is (-182.5 °C).
• Boiling point of methane is (-161.5 °C).
• It is a colourless gas.
• The density of liquid methane is less than that of water.
• Methane is sparingly soluble in water. It is highly soluble in organic solvents like gasoline, ether and alcohol.
• Methane is in gaseous state at room temperature.

Question 20.
Give the uses of methane.
Answer:
Uses of methane are:

• Methane in the form of natural gas is used in industries such as fabric mills, paper mills, food processing industry, petrol purification.
• Being the smallest hydrocarbon, the proportion of CO₂ released in the combustion of methane is small and, therefore, it is used as a domestic fuel.
• Methane is used for production of organic compounds such as ethanol, methyl chloride, methylene chloride and acetylene.

Question 21.
How is methane formed? Give structural formula and electron dot model of methane.
Answer:

• Atomic number of carbon is 6. The electronic configuration of carbon is (2, 4). The valency of carbon is 4.
• Carbon atom can form four covalent bonds with other carbon atoms or atoms of different elements.
• When a carbon atom shares one electron each with four hydrogen atoms and forms four C-H bonds, a methane (CH₄) molecule is formed.
  

Question 22.
What are organic and inorganic compounds?
Answer:
Compounds obtained directly or indirectly from plants and animals are called organic compounds and compounds obtained from minerals are called inorganic compounds.

Question 23.
What is allotropy?
Answer:

• Allotropy – Some elements occur in nature in more than one form.
• The chemical properties of these different forms are the same but their physical properties are different.
• This property of elements is called allotropy.

Question 24.
What are basic organic compounds? What are they also called as?
Answer:

• The compounds formed from only carbon and hydrogen are called basic organic compounds.
• These are also called hydrocarbons.

Write a balanced chemical equation and explain the following chemical reactions.

Question 1.
Preparation of urea from Ammonium cyanate:
Answer:

Organic compound Urea can be synthesized from an inorganic compound Ammonium cyanate.

Question 2.
Coal when burnt in air
Answer:

When coal is burnt in air, the carbon present in coal combines with oxygen present in air to form carbon dioxide gas.

Question 3.
Calcium carbonate reacts with dilute hydrochloric acid:
Answer:

When Calcium carbonate reacts with dilute hydrochloric add it forms Caldum chloride, water and Carbon dioxide gas is evolved.

Question 4.
Carbon dioxide is passed through an aqueous solution of Sodium hydroxide:
Answer:

When Carbon dioxide gas is passed through an aqueous solution of Sodium hydroxide it forms Sodium carbonate and Water.

Question 5.
Carbon dioxide is passed through an aqueous solution of Sodium carbonate:
Answer:

When carbon dioxide is passed through an aqueous solution of Sodium carbonate, it forms Sodium bicarbonate.

Question 6.
Carbon dioxide is passed through freshly prepared lime water for a short duration and then for longer duration:
Answer:

When Carbon dioxide is passed through freshly prepared lime water, it forms water and white precipitate of Calcium carbonate because of which lime water turns milky.

When Carbon dioxide is continuously passed through milky lime water, it forms Calcium bicarbonate which is soluble in water and therefore, water once again turns colourless.

Question 7.
Carbon dioxide gas is dissolved in water.
Answer:

Carboh dioxide gas is fairly soluble in water, it dissolves in water under pressure to form Carbonic acid.

Question 8.
Sodium bicarbonate reacts with dilute Sulphuric acid, (reaction in fire extinguisher):
Answer:

When Sodium bicarbonate reacts with dilute Sulphuric acid it forms Sodium sulphate, water and Carbon dioxide gas.

Question 9.
Methane gas is burnt in air:
Answer:

Methane is highly inflammable, it burns in air with a bluish flame and combines with oxygen present in air to form Carbon dioxide and water. In these reaction 213 kcal/mol of heat is given out.

Question 10.
Methane and Chlorine gases react with each other.
Answer:

Methane and chlorine gases react with each other at the temperature of 250 °C to 400 °C in presence of ultra voilet light and form mainly Methyl chloride (Chloromethane and ‘ Hydrogen chloride)
This reaction is called Chlorination of methane.

Question 11.
Production of methane gas in biogas plant.
Answer:

In biogas plant, microbes act on the bio-degradable complex organic compounds and produce organic acids.

The methanogenic bacteria act on the organic acids to produce Methane gas and Carbon dioxide gas.

Question 12.
Production of water gas:
Answer:

When super heated steam is passed over red hot coke at high temperature, it forms carbon monoxide gas and hydrogen gas.

This gaseous product of carbon monoxide gas and hydrogen gas together is called as water gas.

With the help of ne abelled diagram explain the following:

Question 1.
Regular fire extinguisher.
Answer:

• A fire extinguisher contains Sodium bicarbonate powder. There is also dilute sulphuric acid placed in a glass capsule.
• On pressing the knob, the capsule breaks and sulphuric acid comes in contact with the sodium bicarbonate. These two react chemically to release CO₂ which comes out.
• CO₂ based fire extinguishers do not cause corrosion and are non-conductors of electricity. Therefore, they are used when electrical or electronic equipment catches fire.
• CO₂ based fire extinguishers are used to extinguish small scale fire. It is beyond their capacity to extinguish a big fire.
• In modern fire extinguishers liquid and solid CO₂ is filled under pressure. On reducing the pressure, it becomes gaseous and comes out forcefully through the horn-like hose pipe.
• Chemical reaction:
  

Question 2.
Biogas plant.
Answer:

• Animal dung, dry leaves, wet garbage get decomposed by anaerobic microbes in a biogas plant.
• This produces methane gas, also called biogas.
• Biogas is a very cheap fuel option which meets the demand for cooking gas. It is also used for the production of electricity.
• Biogas contains about 55% to 60% methane and the rest is carbon dioxide.
• Biogas is a fuel which is convenient to use and, in addition to this, a very good manure is also produced as a side product of the process.
• Biogas production process – Production of biogas is an anaerobic process. It takes place in two stages.
  (a) Production of acids – The microbes act on the biodegradable complex organic compound and produce organic acids.
  (b) Methane gas production – The methanogenic bacteria act on the organic acids to produce methane gas.

Chemical reaction:

Answer the following

Question 1.
What happens when substances like milk, sugar, wool, dry leaves, hair and seeds are heated strongly in hard glass test tube?Answer:
When milk, sugar, wool, dry leaves, hair and seeds are heated strongly in hard glass test tube, they get charred and a black substance is left behind. This black substance is carbon.

Answer the following questions:

Question 1.
Take some milk in an evaporating dish. Heat the evaporating dish on a bunsen burner. What remains behind at the bottom of an evaporating dish on complete evaporation of the milk?
Answer:

• On complete evaporation of milk, a black residue is left behind.
• This residue is of carbon.

Question 2.
Take small samples of sugar, wool, dry leaves, hair, seeds, split pulses and plastic in separate test tubes. Heat each test tube and observe the changes taking place in the substances. What does the black substance in each test tube indicate?
Answer:

• On heating the above samples, they get charred and a black substance is left behind.
• The black substance is carbon.

Question 3.
Apparatus : Coal, match box, moist litmus paper, etc.

Procedure : Ignite the coal. Hold the moist blue litmus paper over the gas released on igniting the coal. Note the observation.

(a) With which gas in the air does the coal react on igniting?
Answer:
Coal reacts with oxygen gas present in the air, on igniting.

(b) What is the substance formed?
Answer:
The substance formed is carbon dioxide.

(c) What change takes place in the litmus paper?
Answer:
The moist blue litmus paper turns red.

(d) Write down the chemical reaction taking place in the above procedure.
Answer:
(i) Carbon combines with oxygen to form Carbon dioxide gas.

(ii) This C02 combines with water present on moist blue litmus paper to form Carbonic acid which turns blue litmus to red.

Question 4.
Apparatus : Pencil, electrical wires, battery/ cell, small bulb, water, kerosene, test tube, lead pencils, etc.

Procedure : Remove the lead from a pencil and arrange the apparatus as shown in the above diagram. Note your observations for the following.

(a) What is the colour of lead in the pencil? .
Answer:
The colour of the lead in the pencil is black as it is made from graphite which is an allotrophic form of carbon.

(b) Try to break lead with your hand.
Answer:
The lead breaks easily as it is made up of graphite which is brittle in nature.

(c) Start the electric current in the circuit and observe. What did you find?
Answer:
When we start the electric current in the circuit, the bulb in the circuit glows, indicating that the lead in the pencil is a good conductor of electricity.

(d) Take some water in a test tube. Take some kerosene in another test tube. Put lead dust in both the test tube. What did you observe?
Answer:
(i) Lead dust does not dissolve in water nor in kerosene.
(ii) It remains insoluble in both the test tubes.

Question 5.
Apparatus : Test tube, straw, lime water, etc.

Procedure: Take freshly prepared lime water in a test tube. Blow air in it for some time through the straw and observe the lime water. Note the observation.

(a) What did you see?
Answer:
When we blow air through the straw in freshly prepared lime water, it turns milky.

(b) What might be the reason behind the change?
Answer:

Freshly prepared lime water is obtained by dissolving lime (CaO) in water (H₂O).

When we blow air through the straw in lime water, carbon dioxide (CO₂) present in the air reacts with lime water to form white precipitate (insoluble substance) of Calcium Carbonate (CaCO₃) due to which lime water turns milky.

Question 6.
With the help of a neat labelled diagram explain the laboratory preparation of Carbon dioxide gas.
Answer:
The laboratory preparation of Carbon dioxide gas is as follows:

Apparatus : Retort stand, round bottom flask, thistle funnel, gas delivery tube, gas jars.
Chemicals : Calcium carbonate (Pieces of Shahabad tiles/marble pieces/limestone), dilute hydrochloric acid.

Procedure:

• Assemble the apparatus as shown in the figure. While assembling, place CaCO₃ in the round bottom flask.
• Add dilute HCl in the flask through thistle funnel. See to it that the end of the funnel dips in the acid.
• CO₂ is formed as a result of the reaction between CaCO₃ and HCl. Collect this gas in four to five gas jars. The chemical equation of the above reaction is as follows. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ ↑
  

 

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 10 Information Communication Technology (ICT) Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 10 Information Communication Technology (ICT)

Class 9 Science Chapter 10 Information Communication Technology (ICT) Textbook Questions and Answers

1. Fill in the blanks to complete the statements. Justify the statements.

a. While working with a computer we can read the information stored in its memory and perform other actions in ………………………. memory.
b. While presenting pictures and videos about the works of scientists, we can use ……………………… .
c. To draw graphs based on the quantitative information obtained in an experiment, one uses ……………………… .
d. The first generation computers used to shut down because of ……………………… .
e. A computer will not work unless ………………………. is supplied to it.

2. Answer the following questions.

a. Explain the role and importance of information communication in science and technology.
Answer:

• ICT plays a key role in creating, displaying, collecting, processing and communicating information in the field of science and technology.
• Following is the importance of ICT in science and technology:
  (a) Access to wide range of information
  (b) Storing of Data
  (c) Processing of Data
  (d) Securing work files
  (e) Proper representation of data

b. Which application software in the computer system did you find useful while studying science, and how?
Answer:

• Microsoft word: To write down the information collected and making a document for further evaluation.
• Microsoft excel : To draw graph based on the obtained numerical information from the experiment.
• Internet explorer: To search for information in finding out the solution or solving the queries by reading the available information.

c. How does a computer work?
Answer:

Input unit	Processor	Output Unit
All types of information/ data is entered into the computer through this unit. Generally, a keyboard is used to enter data or information	Processing Unit (1) Memory unit (2) Control unit (3) ALU unit	The result/solution/ answer is eventually sent to the output unit. Generally, a screen/monitor or printer is used as an output unit.

d. What precautions should be taken while using various types of software on the computer?
Answer:

• Antivirus must be installed.
• Software should be legal and from a trusted place.
• Application should be scanned before using.
• Pirated Software should not be used
• Provide all necessary data to obtain the best possible results.

e. Which are the various devices used in information communication? How are they used in the context of science?
Answer:

• Various devices used in information communication are: Computers, Laptops, Mobiles, Radios, Television, etc.
• Computers, Laptops and Mobiles: Help in accessing, collecting, processing, communicating, sharing and storing of information. It helps in determining the appropriate conclusions in all fields, including the field of science.
• Television: Help in getting information about the new and innovative technology.

3. Using a spreadsheet, draw graphs between distance and time, using the information about the movements of Amar, Akbar and Anthony given in the table on page 4, in the lesson on Laws of Motion. What precautions will you take while drawing the graph?

Answer:
Precautions to be taken while drawing a graph:

• The data should be kept in tabular form.
• Whenever there is ‘drag and fill’ option used, ‘smart tag’ option should be used after ‘drag data’ to fill data as required.
• Entered data should be formatted in the manner required.
• Various types of graphs can be created by using the same data, so appropriate graph should be selected.
• Chart titles and axes titles should be updated as per the data.

4. Explain the differences between the different generations of computers. How did science contribute to these developments?
Answer:
Generation: 1st
Time Period: 1946 – 1956
Development: Vacuum Tubes Characteristics:

• Huge in size
• Expensive
• Lot of electricity consumption
• Heat generation

Generation: 2nd
Time Period: 1956 – 1963
Development: Transistors
Characteristics:

• Frequent shutdowns
• Superior to 1st Generation
• Small in size and fast
• Cheaper as compared to 1st Generation
• Less consumption of electricity

Generation: 3rd
Time Period: 1963 -1971
Development: IC
Characteristics:

• Keyboards and monitors
• OS
• Smaller and still cheaper

Generation: 4th
Time Period: 1971 – 2010
Development: Microprocessor Characteristics:

• Use of Internet
• GUI
• Introduction of portable devices like mobiles, laptops, etc.

Generation: 5th
Time Period: 2010 – Till Date
Development: Artificial Intelligence (AI) Characteristics:

• Voice recognition
• Sensors
• Nano technology

1st Generation computers occupied the entire room, but due to advancement in science and technology, today’s computer fits into our pockets.

Initially computers needed a specific language to interact but today we use voice recognition for the same.

In these ways, science has contributed in making the computers faster, smaller, cheaper and much more useful.

5. What devices will you use to share with others the knowledge that you have?
Answer:
Devices like radios, televisions, pendrives, computers, laptops, mobiles, landlines, hard drives, CDs, memory cards help us in sharing our knowledge with others.

6. Using information communication technology, prepare powerpoint presentations on at least three topics in your textbook. Make a flowchart of the steps you used while making these presentations.
Answer:
Steps for preparation of PowerPoint presentations:

7. Which technical difficulties did you face while using the computer? What did you do to overcome them?
Answer:

• Lagging: Due to lot of applications running at the same time, the computer starts lagging and becomes slow. Closing a few applications helped solve the problem of lagging.
• Viruses and Bugs: Cybercrimes are rising daily, even from single mail the computer can be attacked by viruses. Installing a valid antivirus helps solve the problem of viruses and bugs.
• Breach of Privacy: Confidential information being accessed by anyone is the breach of privacy. Putting privacy setting in place helps solve the problem.
• Physical Damage: Hardware over a period of time might get physically damaged. Taking precautions while using will help to solve the problem.

Class 9 Science Chapter 10 Information Communication Technology (ICT) Intext Questions and Answers

Question 1.
Make a list of various hardware and software items of a computer,
Answer:
Hardware: Mouse, Keyboard, Pendrive, Monitor and other parts of computer.
Software: Operating Systems, Application Programs, Antivirus, etc.

Answer the following questions:

Question 2.
Which devices do we directly or indirectly use for collecting, sharing, processing and communicating information?
Answer:

• Computers
• Laptops
• Mobiles
• Memory Cards
• Pendrives
• Landlines
• Hard disks etc.

Question 3.
How is information communication technology important for dealing with explosion of information?
Answer:

• Information explosion means a situation whère information is available in abundance, in other words, too much information.
• Devices like computers, laptops help us in easier accessment of information that we need from all the data.

Class 9 Science Chapter 10 Information Communication Technology (ICT) Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
…………………….. includes communication devices and the use of those devices as well as the services provided with their help.
(a) Operating System
(b) Office
(c) Computers
(d) Information Communication Technology
Answer:
(d) Information Communication Technology

Question 2.
Computers have gone through …………………….. generations.
(a) 5
(b) 7
(c) 10
(d) 8
Answer:
(a) 5

Question 3.
First generation of Computers were considered to be present in the period of ……………………. .
(a) 2000 – 2001
(b) 1901 – 2001
(c) 1946 -1959,
(d) 1996 – 2001
Answer:
(c) 1946-1959

Question 4.
Full form of RAM is ……………………. .
(a) Roaming Application Memory
(b) Random Accessible Media
(c) Random Access Memory
(d) None of the above
Answer:
(c) Random Access Memory

Question 5.
Full form of ROM is ……………………. .
(a) Roaming Only Memory
(b) Random Output Media
(c) Read Only Memory
(d) None of the above
Answer:
(c) Read Only Memory

Question 6.
…………………….. is raw information.
(a) Program
(b) Memory
(c) Data
(d) Operating System
Answer:
(c) Data

Question 7.
…………………….. are used for sharing information.
(a) Telephones
(b) Hard disks
(c) RAM
(d) ROM
Answer:
(a) Telephones

Question 8.
Hard disks are used for …………………….. information.
(a) storing
(b) communicating
(c) sharing
(d) all of the above
Answer:
(a) storing

Question 9.
Computers are used for …………………….. information.
(a) storing
(b) managing
(c) sharing
(d) all of the above
Answer:
(d) All of the above

Question 10.
RAM and ROM are 2 types of …………………….. memory.
(a) external
(b) internal
(c) physical
(d) garbage
Answer:
(b) internal

Question 11.
The information stored in ROM is only …………………….., changes cannot be made.
(a) external memory
(b) readable
(c) accessible
(d) physical
Answer:
(b) readable

Question 12.
…………………….. is a group of commands to be given to the computer.
(a) Program
(b) Memory
(c) Data
(d) Operating System
Answer:
(a) Program

Question 13.
…………………….. communicates between the computer and the person working on it.
(a) Program
(b) Memory
(c) Data
(d) Operating System
Answer:
(d) Operating System

Match the columns:

Column ‘A’	Column ‘B’
(1) Antivirus (2) OS (3) CPU (4) Printer (5) Mouse	a) Output Device b) Software c) Input Device (d) Operating System (e) Brain of the computer

Answer:
(1 – b),
(2 – d),
(3 – e),
(4 – a),
(5 – c)

State whether the following statements are true or false and if false, correct the false statements:

(1) RAM and ROM are the types of external memory.
(2) ICT includes communication devices and the use of those devices as well as services provided with their help.
(3) A computer cannot be used without its operating system.
(4) Microsoft Excel is used to make PowerPoint.
(5) Software refers to the set of commands given to the computer.
Answer:
(1) False. RAM and ROM are the types of internal memory.
(2) True
(3) True
(4) False. Microsoft Excel is used to make spreadsheets.
(5) True

Answer the following in one sentence:

Question 1.
Name the computer which was made between 1946 -1959.
Answer:
The ENIAC computer was made in the period of 1946-1959.

Question 2.
Give one example of Input Unit.
Answer:
Keyboard.

Question 3.
Name the 3 major parts of the processing units.
Answer:

• Memory unit
• Control unit
• ALU unit

Question 4.
What precautions need to the taken care while entering formula into the excel?
Answer:
While using a formula, the ‘=’ sign should be typed first. Similarly, no space should be inserted while typing any formula.

Question 5.
What is Internet Explorer?
Answer:
This is a kind of Search Engine. It helps to find the information we want from all the information available on the internet.

Question 6.
What is a PDF?
Answer:
A PDF or Portable Document Format file can be used to view the file to print it or to handle files.

Question 7.
What is C-DAC?
Answer:
C-D AC, is a well-known Centre for Development of Advanced Computing, situated in Pune.

Write the Full forms of the following abbreviation:

Question 1.
ICT
Answer:
Information Communication Technology

Question 2.
OS
Answer:
Operating System

Question 3.
RAM
Answer:
Random Access Memory

Question 4.
ROM
Answer:
Read Only Memory

Question 5.
CPU
Answer:
Central Processing Unit

Question 6.
DOS
Answer:
Disk Operating System

Question 7.
PDF
Answer:
Portable Document Format

Question 8.
ALU
Answer:
Arithmetic Logical Unit

Question 9.
GUI
Answer:
Graphical User Interface

Question 10.
C-DAC
Answer:
Centre for Development of Advanced Computing

Question 11.
ISCII
Answer:
Indian Script Code for Information Interchange

Define the following:

Question 1.
Memory
Answer:
Memory is the place for storing data obtained from the input and also the generated solution or answer by the computer.

Question 2.
RAM
Answer:
RAM is created from electronic components and can function only as long as it is supplied with electricity.

Question 3.
ROM
Answer:
Information stored in ROM can only be read and changes cannot be made to the information originally stored here.

Question 4.
Operating System
Answer:
It is a program which provides a means of communication between the computer and the person working on it. It is called the DOS (Disk Operating System).

Question 5.
Program
Answer:
A program is a group of commands to be given to a computer.

Question 6.
Data and Information
Answer:
Data is information in its raw (unprocessed) form.

Question 7.
Hardware
Answer:
Hardware consists of all the electronic and mechanical parts used in computers.

Question 8.
Software:
Answer:
Software refers to the commands given to the computer, information supplied to it (input) and the results obtained from the computer after analysis (output).

Give scientific reasons:

Question 1.
Computer cannot function without its operating system.
Answer:

• Operating system is like a link between the computer and the person working on it.
• Operating system manages all the activities performed by the computer.
• Without the operating system, the user won’t be able to input any data or run any program. Thus, a computer cannot run without an operating system.

Question 2.
ROM is a Read Only Memory.
Answer:

• ROM also known as Read Only Memory is a part of internal memory of a computer where the information stored can only be read.
• ROM helps store data permanently for a long period of time and the information stored cannot be deleted.
• Thus, data in a ROM can only be read and cannot be altered or modified and hence, it is called as Read Only Memory.

Complete the table:
Answer:

Answer the following questions:

Question 1.
What precautions will you take when entering data?
Answer:

1. As far as possible, the data should be kept in tabular form. Different types of data should be entered in different cells. Data should be entered neatly and in one ‘flow’. Unnecessary space and special characters should not be used.
2. Many times we ‘drag and fill’ data. At such times, the ‘smart tag’ can be used after ‘drag data’ to fill any data in any manner as required.
3. Once the data has been entered, it can be formatted in different ways. Similarly, we can perform different types of calculations, using different formulae.
4. While using a formula, the ‘=’ sign should be typed first. Similarly, no space should be inserted while typing any formula.

Answer in detail:

Question 1.
Write in short about the opportunities in the field of ICT.
Answer:
(i) Software Field: This is an important field. Having accepted the challenge of creating software, many companies have entered this field. The opportunities in the software field can be classified as follows – application program development, software package development, operating systems and utility development, special purpose scientific applications.

(ii) Hardware Field: Today, there are several companies in our country too, which make computers. They sell computers that they have themselves made. Others sell computers brought from outside as well as repair them and take maintenance contracts to keep computers in big companies working efficiently without a break. Plenty of jobs are available here. There are job opportunities in hardware designing, hardware production, hardware assembly and testing, hardware maintenance, servicing and repairs, etc.

(iii) Marketing: There are many establishments which make and sell computers and related accessories. They need good sales personnel who are experienced in the working of computers as well as skilled in marketing.

(iv) Training: The training of new entrants for various jobs is a vast field. It is very important to have dedicated teachers who are competent in the field of computers.

Question 2.
Write in short about the industries conducting research in the field of computers.
Answer:

• C-DAC, the well-known Centre for Development of Advanced Computing, situated in Pune, is the leading institute in India that conducts research in the field of computers.
• The first Indian supercomputer was made with help from this institute. Valuable guidance for making this computer (the Param computer) was received from the senior scientist Vijay Bhatkar. Param means the supreme.
• This computer can perform one billion calculations per second. It is used in many fields like space research, movements in the interior of the earth, research in oil deposits, medicine, meteorology, engineering, military etc.
• C-DAC has also participated in developing the ISCII code for writing different language scripts. (Indian Script Code for Information Interchange).

Question 3.
Use Microsoft Word to create a document and write equations.
Answer:

• Click on the Microsoft word 2010 icon on the desktop.
• Select the ‘New option in the ‘File’ tab, and then select the ‘Blank document’ option.
• Type your material on the blank page on the screen using the keyboard. Use the language, font size, bold, etc. options in the Home tab to make the typed material attractive.
• To type equations in the text, select the ‘Equation’ option in the ‘Insert’ tab.
  
• Select the proper equation and type it using mathematical symbols.
  

 

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 5 Acids, Bases and Salts Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 5 Acids, Bases and Salts

Class 9 Science Chapter 5 Acids, Bases and Salts Textbook Questions and Answers

1. Identify the odd one out and justify.

(a) Chloride, nitrate, hydride, ammonium
Answer:
Ammonium is the odd one out as it is a basic radical and rest all are acidic radicals. Generally, basic radicals are formed by the removal of electrons from the atom of metals such as Na⁺, Cu²⁺. But there are some exceptions, such as NH₄⁺.

(b) Hydrogen chloride, sodium hydroxide, calcium oxide, ammonia
Answer:
Hydrogen chloride is the odd one out. It is acidic and rest all are basic.

(c) Acetic acid, carbonic acid, hydrochloric acid, nitric acid
Answer:
Carbonic acid is the odd one out. It is a dibasic acid and rest are all monobasic acids.

(d) Ammonium chloride, sodium chloride, potassium nitrate, sodium sulphate
Answer:
Ammonium chloride is the odd one out, as it is made up of a strong acid and weak base and rest all are formed from strong acid and strong base.

(e) Sodium nitrate, sodium carbonate, sodium sulphate, sodium chloride
Answer:
Sodium carbonate is the odd one out, as it is made up of a weak acid and strong base, and rest all are formed from strong acid and strong base.

(f) Calcium oxide, magnesium oxide, zinc oxide, sodium oxide.
Answer:
Zinc oxide is the odd one out, as it is an amphoteric oxide, and rest all are basic oxides.

(g) Crystalline blue vitriol, crystalline common salt, crystalline ferrous sulphate, crystalline sodium carbonate.
Answer:
Crystalline common salt is the odd one out, as it does not contain water of crystallisation. It is an ionic compound and ionic compounds are crystalline in nature and rest all have their crystalline structure because of their water of crystallization.

(h) Sodium chloride, potassium hydroxide, acetic acid, sodium acetate.
Answer:
Acetic acid is the odd one out. It is an acid, the rest are all salts.

2. Write down the changes that will be seen in each instance and explain the reason behind it.

(a) 50ml water is added to 50ml solution of copper sulphate.

Answer:

• Copper sulphate solution is blue. It is a concentrated solution.
• When 50 ml of water is added to this concentrated solution, it becomes a diluted solution.
• The intensity of the blue colour is now different in this homogenous mixture.

(b) Two drops of the indicator phenolphthalein were added to 10ml solution of sodium hydroxide.

Answer:

• Sodiumhy droxide is a base and phenolphthalein is a synthetic indicator.
• Sodium hydroxide solution will turn pink if phenolphthalein is added to it.
• It is a test for identifying bases.

(c) Two or three filings of copper were added to 10ml dilute nitric acid and stirred.
Answer:
When copper metal reacts with dilute nitric acid, the metal does not displace hydrogen from the acid like reaction with other metals. Instead the reaction produces nitric oxide, (NO).

(d) A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.
Answer:
Blue litmus Paper:

• HCl is hydrochloric acid, so the blue litmus turns red.
• When equal amount of NaOH is added the colour again changes to blue and remains the same.

Red litmus paper:

• Red litmus paper shows no colour change in hydrochloric acid.
• When some amount of NaOH is added the colour changes to blue initially but when the amount of NaOH is sufficient the blue colour dissappears.
• Equal amounts of HC1 and NaOH results in the formation of NaCl, a salt, and the solvent water. This reaction is called the neutralization reaction.

(e) Magnesium oxide was added to dilute HCl and magnesium oxide was a added to dilute NaOH.
Answer:
(i) Magnesium oxide + dil HCl.
This is a neutralization reaction. Magnesium oxide is an insoluble base, it reacts with dilute HCl to produce a soluble salt MgCl₂ and water H₂O.
\(\mathrm{MgO}_{(\mathrm{s})}+2 \mathrm{HCl}_{(\mathrm{aq})} \longrightarrow \mathrm{MgCl}_{2(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}_{(n)}\)

(ii) Magnesium oxide + NaOH.
No chemical reaction takes place between magnesium oxide and sodium hydroxide.

(f) Zinc oxide was added to dilute HCl and zinc oxide was added to dilute NaOH.
Answer:

• Zinc oxide reacts with dilute hydrochloric acid to form zinc chloride and water. It is a neutralization reaction.
  \(\mathrm{ZnO}_{(\mathrm{s})}+2 \mathrm{HCl}_{(\mathrm{aq})} \longrightarrow \mathrm{ZnCl}_{2(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})}\)
• Zinc oxide reacts with sodium hydroxide to form sodium zincate and water.
  \(\mathrm{ZnO}_{(\mathrm{s})}+2 \mathrm{NaOH}_{(\mathrm{aq})} \longrightarrow \mathrm{Na}_{2} \mathrm{ZnO}_{2(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{t})}\)

(g) Dilute HCl was added to limestone.
Answer:

• When hydrochloric acid is added to limestone, carbon dioxide is liberated. Limestone is calcium carbonate.
  CaCO₃ + 2 HCl → CaCl₂ + CO₂ + H₂O
• Carbon dioxide is prepared in the laboratory using these chemicals.

(h) Pieces of blue vitriol were heated in a test tube. On cooling, water was added to it.
Answer:

• On heating, the crystalline structure of blue vitriol breaks down to form a colourless powder and water is released.
• This water is part of the crystal structure of blue vitriol.
• It is called water of crystallization.
• On adding water to the white powder, a solution was formed which has the same colour as the copper sulphate salt solution.

(i) Dilute H₂SO₄ was taken in an electrolytic cell and electric current was passed through it.
Answer:

• If pure water is used in the electrolytic cell, current does not flow even on putting on the switch.
• Pure water is a bad conductor of electricity. Dilute H₂SO₄ is acidulated water.
• The electrical conductivity of water increases on mixing with strong acid or base in it due to their dissociation and electrolysis of water takes place.
• H₂SO₄ is fully dissociated in aqueous solution. \(\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow 2 \mathrm{H}^{+}+\mathrm{SO}_{4}^{2-}\)
• H₂O is a weak electrolyte and is only slightly dissociated \(\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{H}^{+}+\mathrm{OH}^{-}\)
• During electrolysis, the hydrogen ions migrate towards the cathode and are discharged there.

[H+ ions gains electrons and are converted to hydrogen gas]
\(2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}\)
Cathode reaction:
\(2 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{i})}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}+2 \mathrm{OH}_{(\mathrm{aq})}^{-}\)
Anode reaction:
\(2 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \longrightarrow \mathrm{O}_{2(\mathrm{~g})}+4 \mathrm{H}_{(\mathrm{aq})}^{+}+4 \mathrm{e}\)

• For every hydrogen ion discharged at the anode, another hydrogen ion is formed at the cathode.
• The net result is that the concentration of the sulphuric acid remains constant and electrolysis of water is overall reaction. \(2 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{H}_{2}+\mathrm{O}_{2}\)
• The volume of the hydrogen gas formed near the cathode is double that of the oxygen gas formed near the anode.

3. Classify the following oxides into three types and name the types.
CaO, MgO, CO₂, SO₃, Na₂O, ZnO, Al₂O₃, Fe₂O₃
Answer:
There are three types of oxides : Basic oxides, Acidic oxides and Amphoteric oxides.

Basic oxides	Acidic oxides	Amphoteric oxides
CaO	CO2	ZnO
MgO	SO3	Al2O3
Na2O
Fe2O3

Generally metal oxides are basic in nature.
Exception : Al₂O₃ and ZnO are amphoteric oxides.
Generally non-metal oxides are acidic in nature.

4. Explain by drawing a figure of the electronic configuration.

a. Formation of sodium chloride from sodium and chlorine.
Answer:

b. Formation of a magnesium chloride from magnesium and chlorine.
Answer:

5. Show the dissociation of the following compounds on dissolving in water, with the help of chemical equation and write whether the proportion of dissociation is small or large.
Hydrochloric acid, Sodium chloride, Potassium hydroxide, Ammonia, Acetic acid, Magnesium chloride, Copper sulphate.
Answer:
(a) Hydrochloric acid (HCl)

• \(\mathrm{HCl}_{(g)} \frac{\text { Water }}{\text { dissociation }}>\mathrm{H}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{(\mathrm{aq})}^{-}\)
• Hydrochloric acid is a strong acid, as on dissolving in water, it dissociates almost completely and the resulting aqueous solution contains mainly H ions and the concerned acidic radical.
• The proportion of dissociation is large.

(b) Sodium chloride (NaC1)

• \(\mathrm{NaCl}_{(s)} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Na}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{\text {(aq) }}^{-}\)
• When an ionic compound begins to dissolve in water, the water molecules push themselves in between the positive and negative ions of the compound and separate them from each other.
• The proportion of dissociation is large.

(c) Potassium hydroxide (KOH)

• \(\mathrm{KOH}_{(n)} \frac{\text { Water }}{\text { dissociation }} \mathrm{K}_{(\mathrm{aq})}^{+}+\mathrm{OH}_{(\mathrm{aq})}\)
• Potassium hydroxide is a strong base, as on dissolving in water, it dissociates almost completely and the resulting aqueous solution contains mainly OH⁺ ions and the concerned basic radical.
• The proportion of dissociation is large.

(d) Ammonia (NH₃)
(i) \(\mathrm{NH}_{3(\mathrm{~g})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{n}}-\frac{\text { Water }}{\text { uissociation }}>\mathrm{NH}_{4 \text { (aq) }}^{+}+\mathrm{OH}_{\text {(aq) }}^{-}\)
(ii) Ammonia dissolves in water to form NH₄OH (ammonium hydroxide). NH₄OH does not dissociate completely as it is a weak base. The aqueous solution contains a small proportion of OH^– ions and the concerned basic radical along with a large proportion of undissociated molecules of the base i.e. NH₄OH.
(iii) The proportion of dissociation is small.

(e) Acetic acid (CH₃COOH)

• \(\mathrm{CH}_{3} \mathrm{COOH}_{(l)} \frac{\text { Water }}{\text { dissociation }} \mathrm{CH}_{3} \mathrm{COO}_{(\text {aq) }}+\mathrm{H}_{(a z)}+{ }^{+}\)
• Acetic acid is a weak acid, on dissolving in water it does not dissociate completely, and the resulting aqueous solution contains H⁺ ion and the concerned acidic radical in small proportion along with large proportion of the undissociated molecules of the acid.
• The proportion of dissociation is small.

(f) Magnesium chloride (MgCl₂)

• \(\mathrm{MgCl}_{2(\mathrm{~s})} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Mg}^{2+} \text { (aq) }+2 \mathrm{Cl}^{-} \text {(aq) }\)
• Magnesium chloride dissolves in water and forms magnesium ions and chloride ions. When an ionic compound begins to dissolve in water, the water molecules push themselves in between the ions of the compound and separate them from each other.
• The proportion of dissociation is large.

(g) Copper sulphate (CuSO₄)

• \(\mathrm{CuSO}_{4(s)} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Cu}_{(\mathrm{aq})}^{2+}+\mathrm{SO}_{4}^{2-}\)
• When Copper sulphate is dissolved in water it forms copper ions and sulphate ions. When an ionic compound begins to dissolve in water, water molecules push themselves in between the ions of the compound and separate them from each other.
• The proportion of dissociation is large.

6. Write down the concentration of each of the following solutions in g/L and mol/L.

a. 7.3g HCl in 100ml solution
b. 2g NaOH in 50ml solution
c. 3g CH₃COOH in 100ml solution
d. 4.9g H₂SO₄ in 200ml solution
Answer:
To find : The concentration in g/L.
Solution:

7. Obtain a sample of rainwater. Add to it a few drops of universal indicator. Meausre its pH. Describe the nature of the sample of rainwater and explain the effect if it has on the living world.
Answer:

• pH of rain water is 6.5 that means rain water is slightly acidic.
• When we add universal indicator to rain water it turns orangish red, indicating pH value is between 0 to 7, which tells us that rain water is acidic in nature.
• Most of the plants grow best when pH of soil is close to 7. If the soil is too acidic or too basic, it affects plant growth.

8. Answer the following questions.

a. Classify the acids according to their basicity and give one example of each type.
Answer:

• Basicity of acids : The number of H⁺ ions obtainable by the dissociation of one molecule of an acid is called its basicity. The acids are classified as monobasic, dibasic and tribasic acids based on the number of H⁺ ions present.
• Examples of monobasic acid : HCl, HNO₃, CH₃COOH
• Examples of dibasic acid: H₂SO₄, H₂CO₃
• Examples of tribasic acid: H₃BO₃, H₃PO₄

b. What is meant by neutralization? Give two examples from everyday life of the neutralization reaction.
Answer:

• In neutralization reaction, an acid reacts with a base to form salt and water.
• In a neutralisation reaction the acid dissociates to form H⁺ ions and base dissociates to form OH ions.
• They combine to form H₂O molecules which mixes with the solvent.

Examples in daily life:

• When people suffer from acidity, they take some antacids to neutralise the acid in their stomach.
• If an ant stings us the pain is due to formic acid. It is neutralised by rubbing moist baking soda which is basic in nature.

c. Explain what is meant by electrolysis of water. Write the electrode reactions and explain them.
Answer:
Electrolysis of water:

• Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to an electric current being passed through acidified water.
• Cathode reaction:
  \(2 \mathrm{H}_{2} \mathrm{O}_{(l)}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}+2 \mathrm{OH}_{(\mathrm{aq}}\)
• Anode reaction:
  \(2 \mathrm{H}_{2} \mathrm{O}_{(l)} \longrightarrow \mathrm{O}_{2(\mathrm{~g})}+4 \mathrm{H}_{(\mathrm{aq})}^{+}+4 \mathrm{e}^{-}\)
• It is found that the volume of gas formed near the cathode is double that of the gas formed near the anode.
• Hydrogen gas is formed near the cathode and oxygen gas near the anode.
• From this, it is clear that electrolysis of water has taken place and its constituent element have been released.

9. Give a reason for the following.

a. Hydronium ions are always in the form H₃O⁺.
Answer:

• Acids in water gives H⁺ ions. These H⁺ ions do not exist freely in water.
• This is because H⁺ is a single proton, a hydrogen atom has only one proton and one electron.
• If the electron is removed to make H⁺, all that is left is an extremely tiny positively charged nucleus.
• This H ion will immediately combine with the surrounding water (H₂O) molecules to form (H₃O₄) hydronium ion.

b. Buttermilk spoils if kept in a copper or brass container.
Answer:

• Buttermilk contains an organic acid called as lactic acid.
• The lactic acid reacts with copper and brass and forms toxic compounds which are not fit for consumption.
• They are harmful and may cause food poisoning.
• So it is not advisable to keep buttermilk in brass or copper containers.

10. Write the chemical equations for the following activities.

(a) NaOH solution was added to HCl solution.
Answer:
When NaOH reacts with HCl, it gives NaCl and water.

(b) Zinc dust was added to dilute H₂SO₄.
Answer:
When zinc reacts with dilute sulphuric acid, it forms zinc sulphate and hydrogen gas is liberted.

(c) Dilute nitric acid was added to calcium oxide.
Answer:
When dilute nitric acid reacts with calcium oxide, it forms calcium nitrate and water.

(e) Carbon dioxide gas was passed through KOH solution.

(f) Dilute HCl was poured on baking soda.

11. State the differences.

a. Acids and bases
Answer:

Acids	Bases
(i) A substance which liberates H+ ions when dissolved in water is an acid (ii) Blue litmus turns red in an acid. (iii) The pH of an acid is less than 7. (iv) Acids are sour to taste (v) e.g. HCl, H2SO4	A substance which liberates OH– ions when dissolved in water is called a base. Red litmus turns blue in a base The pH of a base is greater than 7. Bases are bitter to taste, e.g. NaOH, KOH.

b. Cation and anion
Answer:

Cations	Anions
(i) Cations are ions with a net positive charge.	Anions are ions with a net negative charge.
(ii) Cations are generally formed by metals. When metals donate electrons, they have excess of protons, hence they form cations.	Anions are generally formed by non-metals. When non-metals accept electrons, they have excess of electrons, hence they form anions.
(iii) Cations are attracted towards the cathode which are negatively charged electrodes.	Anions are attracted towards the anode which are positively charged electrodes.
(iv) e.g.: Na+, Ca2+, Mg2+, K+ etc.	e.g.: O2 , S2-, Cl–, Br– etc.

c. the Negative electrode and the positive electrode.

Answer:

Negative Electrode	Positive Electrode
(i) Negatively charged electrodes are called as a cathode.	Positively charged electrodes are called as Anode.
(ii) Positively charged cations move towards the cathode or negative electrode.	Negatively charged anions move towards the anode or positive electrode.
(iii) Cathode accepts electrons from cations	Anode gives electrons to anions

12. Classify aqueous solutions of the following substances according to their pH into three groups : 7, more than 7, less than 7.

Common salt, sodium acetate, hydrochloric acid, carbon dioxide, potassium bromide, calcium hydroxide, ammonium chloride, vinegar, sodium carbonate, ammonia, sulphur dioxide.
Answer:

pH = 7	pH > 7	pH < 7
(a) common salt.	sodium acetate.	sulphur dioxide.
(b) potassium bromide.	sodium carbonate	hydrochloric acid.
(c)	ammonia.	carbon-dioxide.
(d)	calcium hydroxide.	ammonium chloride.
(e)		vinegar

Class 9 Science Chapter 5 Acids, Bases and Salts Intext Questions and Answers

Question 1.
How are the following substances classified into three groups with the help of litmus?
Lemon, tamarind, baking soda, buttermilk, vinegar, orange, milk, lime, tomato, milk of magnesia, water, alum.
Answer:

Basic Substance: Turns Red Litmus Blue	Acidic Substance: Turns Blue Litmus Red	Neutral Substance: No change in the colour of litmus
Baking Soda	Lemon	water
Lime	Tamarind
Milk of Magnesia	Buttermilk
	Vinegar
	Orange
	Milk
	Tomato
	Alum

Question 2.
Fill in the columns in the part of the following table:
Answer:

Question 3.
Complete the following table of the concentration of various aqueous solutions.
Answer:

Question 4.
Complete the following table of neutralization reactions and also write down the names of the acids, bases and salts in it.
Answer:

Question 5.
What are the names of the following compounds? NH₃, Na₂O, CaO.
Answer:
NH₃ : Ammonia
Na₂O : Sodium oxide
CaO : Calcium oxide

Question 6.
Into which type will you classify the above compounds, acid, base or salt?
Answer:
NH₃ : base
Na₂O : base
CaO : base

Question 7.
ive examples of monobasic, dibasic and tribasic acids.
Answer:
Monobasic acid examples: HNO₃, HCl, CH₃COOH
Dibasic acid examples: H₂SO₄, H₂CO₃
Tribasic acid examples: H₃BO₃, H₃PO₄

Question 8.
Give the three types of bases with their examples.
Answer:
Types of bases:
Monoacidic base examples : NaOH, KOH, NH₄OH
Diacidic base examples: Ca(OH)₂, Ba(OH)₂
Triacidic base examples: A(OH)₃, Fe(OH)₃

Question 9.
What are the colours of the following natural and synthetic indicators in acidic and basic solutions? Litmus, turmeric, jamun, methyl orange, phenolphthalein?
Answer:

Indicator	Colour in Acidic Solution	Colour in basic Solution
Litmus	Red	Blue
Turmeric	Yellow	Red
Jamun	Red	Blue-Green
Methyl orange	Red	Yellow
Phenolphthalein	Colourless	Pink

Question 10.
On mixing the substances as shown here, what are the resulting mixtures formed by mixing the following substances called?
(a) Water and salt
(b) Water and sugar
(c) Water and sand
(d) Water and sawdust
Answer:
(a) Water and salt – Homogeneous mixture
(b) Water and sugar – Homogeneous mixture
(c) Water and sand – Heterogeneous mixture
(d) Water and sawdust – Heterogeneous mixture

Question 11.
What would be the definition of an acid and a base with reference to the neutralization reaction?
Answer:

• Acid: An acid is a substance which neutralises a base to form salt and water.
• Base: A base is a substance which neutralises an acid to form salt and water.

Answer the following questions:

Question 1.
Take aqueous solution of sodium chloride, copper sulphate, glucose, urea, dil.H₂SO₄ and dil.NaOH in a beaker and test the electrical conductivity of the solutions. Answer the given below questions.

(a) With which solutions did the bulb glow?
Answer:
Solutions with which bulb glows: Aqueous solution of NaCl, CuSO₄, H₂SO₄ and NaOH.

(b) Which solutions are electrical conductors?
Answer:
Solutions which are electrical conductors:
NaCl, CuSO₄, H₂SO₄ and NaOH.

Question 2.
During electrolysis of copper sulphate, if electric current is passed through the electrolytic cell for a long time, what change would be seen at the anode?
Answer:

• When electricity is passed for a long time through copper sulphate solution, the following reaction is seen at the anode: Anode Reaction: Cu(s) → Cu²⁺(aq) + 2e^–
• All the copper atoms will get converted into copper ions and get deposited on the cathode. This process continues till the copper anode exists.

Question 3.
Would water be a good conductor of electricity?
Answer:
Pure water is not a good conductor of electricity.

Answer the following questions:

Question 1.
(i) With which solutions did the bulb glow?
(ii) Which solutions are electrical conductors?

Answer:
(i) The bulbs glows when the wire are immersed in NaCl solution.
(ii)

Solution	Results
1g Copper Sulphate Solution	Bulb glow
1g Glucose Solution	Bulb does not glow
1g Urea Solution	Bulb does not glow
5ml dil.H2SO4 Solution	Bulb glows
5ml dil. NaOH Solution	Bulb glows

Question 2.
What would be the definition of an acid and a base with reference to the neutralization reaction?
Answer:

• Acid: An acid is a substance which neutralises a base to form salt and water.
• Base: A base is a substance which neutralises an acid to form salt and water.

Question 3.
Dissolve 2g salt in 500ml pure water. Take 250 ml of this solution in a 500ml capacity beaker. Connect two electrical wires to the positive and negative terminals of a power supply. Remove the insulating cladding from about 2cm portions at the other ends of the wires. These are the two electrodes. Fill two test tubes upto the brim with the prepared dilute salt solution. Invert them on the electrodes without allowing any air to enter. Start the electric current under 6V potential difference from the power supply. Observe what happens in the test tubes after some time.
(a) Did you see the gas bubbles forming near the electrodes in the test tubes?
(b) Are these gases heavier or lighter than water?
(c) Are the volumes of the gases collected over the solution in the two test tubes the same or different?
(d) Test the solutions in the two test tubes with litmus paper, what do you see?
(e) Repeat the activity by using dilute H₂SO₄ as well as dilute NaOH as the electrolyte.
Answer:
(a) Yes, gas bubbles can be seen forming near the electrodes in the test tube.
(b) These gases are lighter than water.

(c) The volumes of gases collected over the solution in the two test tubes are different.
(d) The solution in the cathode turns red litmus blue while solution in anode turns blue litmus red.
(e) When the above experiment is repeated with dil H₂SO₄ and dil NaOH, Hydrogen gas is liberated at cathodes and oxygen gas is liberated at anode.

Answer the following questions:

Question 1.
Cut a lemon into two equal parts. Take the juice of each part into two separate beakers. Pour 10 ml of drinking water in one beaker and 20 ml in the second. Stir the solutions in both the beakers and taste them. Is there any difference in the tastes of the solutions in the two beakers? What is that difference?
Answer:

• In the above activity, the sour taste of the solutions is because of the solute, lemon juice in them.
• The quantity of the lemon juice is the same in both the solutions. Yet their tastes are different.
• The solution in the first beaker is more sour than the one in the second.
• Although the quantity of the solute is the same in both the solutions, the quantity of the solvent is different.
• Ratio of the quantity of the solute to the quantity of the resulting solution is different. This ratio is larger for the solution in the first beaker and therefore that solution tastes more sour.
• On the other hand, the proportion of the lemon juice in the total solution in the second beaker is smaller and taste is less sour.
• The taste of foodstuff depends upon the nature of the taste-giving ingredient and its proportions in the foodstuff.
• Similarly, all the properties of a solution depend on the nature of the solute and solvent and also on the proportion of the solute in a solution
• The proportions of a solute in a solution is called the concentration of the solute in the solution.

Question 2.
Take a big test tube. Choose a rubber stopper in which a gas tube can be fitted. Take a few pieces of magnesium ribbon in the test tube and add some dilute HCl to it. Take a lighted candle near the end of the gas tube and observe. What did you observe?

Answer:

• Magnesium metal reacts with dilute HCl and an inflammable gas, hydrogen, is formed.
• During this reaction, the reactive metal displaces hydrogen from the acid to release hydrogen gas.
• At the same time, the metal is converted into basic radical which combines with the acidic radical from the acid to form the salt.
  \(\mathrm{Mg}_{(\mathrm{s})}+2 \mathrm{HCl}_{(\mathrm{aq}) \longrightarrow} \underset{\rightarrow}{\mathrm{MgCl}_{2(\mathrm{aq})}}+\mathrm{H}_{2(\mathrm{~g})}\)

Question 3.
Take some water in a test tube and add a little red oxide (the primer used before painting iron articles) to it. Now add a small quantity of dilute HCl to it, shake the test tube and observe.
(a) Does the red oxide dissolve in water?
(b) What change takes place in the particles of red oxide on adding dilute HCl?
Answer:
(a) The chemical formula of red oxide is Fe₂O₃. It is insoluble in water.
(b) The water-insoluble red oxide reacts with HCl to produce a water-soluble salt FeCl₃.

• This gives a yellowish colour to the water.
• The following chemical equation can be written for this chemical change.
  \(\mathrm{Fe}_{2} \mathrm{O}_{3(\mathrm{~s})}+6 \mathrm{HCl}_{(\mathrm{aq})} \longrightarrow 2 \mathrm{FeCl}_{3(\mathrm{aq})}+3 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})}\)

Question 4.
Fit a bent tube in a rubber cork. Take some lime water in a test tube and keep it handy. Take some baking soda in another test tube and add some lemon juice to it. Immediately fit the bent tube over it. Insert its other end into the lime water. Note down your observations of both the test tubes. Repeat the procedure using washing soda, vinegar and dilute HC1 properly. What do you see?
Answer:

• In this activity, when limewater comes in contact with the gas released in the form of an effervescence, it turns milky.
• This is a chemical test for carbon dioxide gas.
• When lime water turns milky, we infer that the effervescence is of CO₂.
• This gas is produced on the reaction of acids with carbonate and bicarbonate salts of metals.
• A precipitate of CaCO₃ is produced on its reaction with the lime water Ca(OH)₂.
• This reaction can be represented by the following chemical equation.
  \(\mathrm{Ca}(\mathrm{OH})_{2(\mathrm{aq})}+\mathrm{CO}_{2(\mathrm{~g})} \longrightarrow \mathrm{CaCO}_{3(\mathrm{~s})}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})}\)
• Washing soda is sodium carbonate Na2CO₃. It will react same as baking soda (NaHCO₃).
• Vinegar and HCl are acids, they do not react chemically with lemon juice.

Class 9 Science Chapter 5 Acids, Bases and Salts Additional Important Questions and Answers

Select the correct option

Question 1.
…………………. acid is present in lemon.
(a) malic acid
(b) tartaric acid
(c) citric acid
(d) butyric acid
Answer:
(c) Citric acid

Question 2.
Tamarind contains …………………. acid.
(a) Lactic acid
(b) tartaric acid
(c) matlic acid
(d) butyric acid
Answer:
(b) tartaric

Question 3.
Butter milk contains …………………. acid.
(a) butyric acid
(b) Lactic acid
(c) matlic acid
(d) citric acid
Answer:
(a) Butyricacid

Question 4.
If the basic radical is H+ the type of compound is ………………… .
(a) neutral
(b) base
(c) acid
(d) alkali
Answer:
(c) Acid

Question 5.
The name of compound NH3 is ………………… .
(a) nitric acid
(b) ammonium
(c) nitride
(d) ammonia
Answer:
(b) ammonia

Question 6.
The bases which are soluble in water are called as ………………… .
(a) indicators
(b) acids
(c) alkalis
(d) salts
Answer:
(c) alkalis

Question 7.
H₃PO₄ is a …………………. acid.
(a) monobasic
(b) tribasic
(c) tetrabasic
(d) dibasic
Answer:
(b) tribasic

Question 8.
According to pH scale pure water has a pH of ………………… .
(a) 6
(b) 7
(c) 5
(d) 8
Answer:
(b) 7

Question 9.
With reference to neutralization, metallic oxides are ………………… in nature.
(a) basic
(b) neutral
(c) acidic
(d) saline
Answer:
(a) basic

Question 10.
Molecular formula of blue vitriol is ………………… .
(a) CuSO₃ 5H₂O
(b) CuSO₄ 4H₂O
(c) CUSO₃ 4H₂O
(d) CUSO₄ 5H₂O
Answer:
(d) CUSO₄ 5H₂O

Question 11.
Molecular formula of crystalline alum is ………………… .
(a) KSO₄, AISO₄, 24H₂O
(b) K₂SO₄, ALSO₄, 24H₂O
(c) K₂SO₄, AL₂(SO₄)₃, 24H₂O
(d) KSO₄, Al₂(SO₄)₃, 24H₂O
Answer:
(c) K₂SO₄, AL₂(SO₄)₃, 24H₂O

Question 12.
Molecular formula for sodium oxide is ………………… .
(a) Na₂O
(b) NaO₂
(c) NaO
(d) Na₂O₂
Answer:
(a) Na₂O

Question 13.
H₂CO₃ is …………………. acid.
(a) monobasic
(b) dibasic
(c) tribasic
(d) tetrabasic
Answer:
(b) dibasic

Question 14.
Molecular formula of Red oxide is ………………… .
(a) Fe₂O₃
(b) CuO
(c) Fe₃O₄
(d) Na₂O
Answer:
(a) Fe₂O₃

Question 15.
The positive terminal electrode is called as ………………… .
(a) anode
(b) cathode
(c) anion
(d) cation
Answer:
(a) anode

Question 16.
…………………. produced in stomach helps in digestion.
(a) Hydrochloric acid
(b) Oxalic acid
(c) Sulphuric acid
(d) Nitric acid?
Answer:
(a) Hydrochloric acid

Question 17.
The solution turns blue litmus red, its pH is likely to be ………………… .
(a) 7
(b) 4
(c) 14
(d) 9
Answer:
(b) 4

Question 18.
An ionic compound NaCl is formed by ………………… .
(a) Na⁺ and Cl^–
(b) Na⁺ and Cl⁺
(c) Na^– and Cl^–
(d) Na^– and Cl⁺
Answer:
(a) Na⁺ and Cl^–

Question 19.
pH of strong acid is ………………… .
(a) 0
(b) 7
(c) 8
(d) 14
Answer:
(a) 0

Question 20.
HCl + NaOH → NaCl + H₂O is a …………………. reaction.
(a) neutralization
(b) crystallisation
(c) electrolysis
(d) dissociation
Answer:
(a) neutralization

Question 21.
Adding water to acid is an …………………. reaction.
(a) endothermic
(b) exothermic
(c) neutralisation
(d) crystallisation
Answer:
(b) exothermic

Find the odd one out:

(a) Rose Petal, Turmeric, Phenolphthalein, Indigo.
Answer:
Phenolphthalein is odd one out as rest are natural indicators while phenolphthalein is a synthetic indicator.

(b) Lime water, Vinegar, Acetic acid, Tartaric acid.
Answer:
Lime water is odd one out as this is basic in nature while rest are acidic.

(c) NaHCO₃, HCl, H₂SO₄, HNO₃
Answer:
NaHCO₃ is odd one out as it is base while rest are acids.

(d) Oxalic acid, Nitric acid, Citric acid, acetic acid.
Answer:
Nitric acid is odd one out as others are weak acids while Nitric acid is a strong acid.

(e) Crystalline, Liquid, Gases, Solid.
Answer:
Crystalline is odd one out as this is nature of a compound while others are physical states of compounds.

(f) Ca(OH)₂, Mg (OH)₂, NaOH, NH₄OH.
Answer:
NaOH is odd one out even though all are bases but NaOH is highly soluble in water compared to others.

Name the following:

Question 1.
Name the three types of ionic compounds.
Answer:
The three types of ionic compounds are acids, bases and salts.

Question 2.
Name the two constituents of molecule of an ionic compound.
Answer:

• Cation (positive ion/ basic radical)
• Anion (negative ion/acidic radical).

Question 3.
Name any three acids with their molecular formula.
Answer:

• Hydrochloric acid – HC1
• Sulphuric acid – H₂SO₄
• Nitric acid – HNO₃

Question 4.
Name any three bases with their molecular formula.
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH
• Calcium hydroxide – Ca(OH)₂

Question 5.
Name any three salts with their molecular formula.
Answer:

• Sodium chloride – NaCl
• Potassium sulphate – K₂ SO₄
• Calcium chloride – CaCl₂

Question 6.
Name any two strong acids.
Answer:

• Hydrochloric acid – HC1
• Sulphuric acid – H₂ SO₄

Question 7.
Name any two weak acids.
Answer:

• Acetic acid – CH₃ COOH
• Carbonic acid – H₂ CO₃

Question 8.
Name any two strong bases.
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH

Question 9.
Name a weak base.
Answer:
Ammonium hydroxide – NH₄OH

Question 10.
Name any two alkalis.
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH

Question 11.
Name any two acids with their basicity 1 (monobasic)
Answer:

• Hydrochloric acid – HC1
• Nitric acid – HNO₃

Question 12.
Name any two acids with their basicity 2 (dibasic)
Answer:

• Sulphuric acid – H₂ SO₄
• Carbonic acid – H₂CO₃

Question 13.
Name any two acids with their basicity 3 (tribasic)
Answer:

• Boric acid – H₃BO₃
• Phosphoric acid – H₃PO₄

Question 14.
Name any two bases with their acidity 1 (monoacidic)
Answer:

• Sodium hydroxide – NaOH
• Potassium hydroxide – KOH

Question 15.
Name any two bases with their acidity 2 (diacidic)
Answer:

• Calcium hydroxide – Ca(OH)₂
• Barium hydroxide – Ba(OH)₂

Question 16.
Name any two bases with their acidity 3 (triacidic)
Answer:

• Aluminium hydroxide – Al(OH)₃
• Ferric hydroxide – Fe(OH)₃

Question 17.
Name the two units to express the concentration of the solution.
Answer:

• mass of solute in grams dissolved in one litre of the solution grams per litre, (g/L).
• Number of moles of the solute dissolved in one litre of the solution. Molarity (M) of the solution.

Match the columns:

Question 1.

Column ‘A’	Column ‘B’
(1) HNO3 (2) H3PO4 (3) CH3COOH (4) H2CO3	(a) Acetic acid (b) Carbonic acid (c) Phosphoric acid (d) Nitric acid

Answer:
(1-d),
(2- c),
(3 – a),
(4 – b)

Question 2.

Column ‘A’	Column ‘B’
(1) NH4OH (2) Ca(OH)2 (3) Al(OH)3 (4) Ba(OH)2	(a) Aluminium Hydroxide (b) Barium Hydroxide (c) Calcium Hydroxide (d) Ammonium Hydroxide

Answer:
(1-d),
(2- c),
(3 – a),
(4 – b)

Question 3.

Column ‘A’ Solution		Column ‘B’ pH
(1)	Milk	(a)	0
(2)	Milk of Magnesia	(b)	14
(3)	1 M HCl	(c)	10.5
(4)	1 M NaOH	(d)	6.5

Answer:
(1-d),
(2- c),
(3 – a),
(4 – b)

Question 4.

Column ‘A’	Column’B’
(1) Urine (2) Apples (3) Orange (4) Butter	(a) Butyric acid (b) Uric acid (c) Malic acid (d) Citric acid

Answer:
(1 – b),
(2 – c),
(3 – d),
(4 – a)

Question 5.

Column ‘A’	Column ‘B’
(1) Crystalline blue vitriol (2) Crystalline green vitriol (3) Crystalline (4) washing soda Crystalline alum	(a) FeS04-7H20 (b) K2S04-A12(S04)3.24H20 (c) CuS04-5H20 (d) Na2CO310H2O

Answer:
(1-c),
(2- a),
(3 – d),
(4 – b)

State whether the following statements are true or false and if false. Correct the false statement:

(1) The separation of H and CI in HCI is in absence of water.
(2) \(\mathrm{NaOH}_{(\mathrm{s})} \frac{\text { Water }}{\text { dissociation }}>\mathrm{Na}_{(\mathrm{aq})}^{+}+\mathrm{OH}_{(\mathrm{aq})}^{-}\)
(3) H₂SO₄ is a strong acid.
(4) NaC1 is an ionic compound.
(5) Turmeric is synthetic indicator.
(6) Metal + Dilute acid forms salt and water.
(7) Copper oxide is called red primer.
(8) Oxide of non-metal + Acid → Salt + Water.
(9) Zinc oxide reacts with sodium hydroxide to form sodium zincate.
(10) Al₂O₃ is an amphoteric oxide.
(11) Blue vitriol ZnSO₄. 7H₂O.
(12) Molecular formula for crystalline Ferrous sulphate is Fe5O₄. 5H₂O.
(13) NaCl in water does not conduct electricity.
(14) Phenolphthalein is colourless in base.
Answer:
(1) False. The separation of H⁺ and Cl^– in HC1 is in presence of water.
(2) True
(3) True
(4) True
(5) False. Turmeric is a natural indicator.
(6) False. Metal + Dilute acid forms salt and hydrogen gas.
(7) False. Iron oxide is called red primer.
(8) False. Oxide of izan-metal + Base → Salt + Wafer.
(9) True
(10) True
(11) False. Blue Vitriol is CuSO₄. 5H₂O.
(12) False. Molecular formula for crystalline Ferrous sulphate is FeSO₄. 7H₂O.
(13) False. NaCl in water conducts electricity.
(14) False, Phenolphthalein is colourless in acid and pink in base.

Define the following:

Question 1.
Acid
Answer:
An acid is a substance which on dissolving in water gives rise to H ion as the only cation. For example, HC1, H₂ SO₄, H₂CO₃.

Question 2.
Base
Answer:
A base is a substance which on dissolving in water gives rise to the OW ion as the only anion. For, NaOH, Ca(OH)₂

Question 3.
Strong Acid
Answer:
On dissolving in water, a strong acid dissociates almost completely, and the resulting aqueous solution contains mainly H ions and the concerned acidic radical. e.g. HC1, HBr, HNO₃, H₂SO₄.

Question 4.
Weak Acid
Answer:
On dissolving in water a weak acid does not dissociate completely, and the resulting aqueous solution contains H+ ion and the concerned acidic radical in small proportion along with large proportion of the undissociated molecules of the acid, e.g., H₂CO₃ (Carbonic acid), CH₃COOH (Acetic acid)

Question 5.
Strong Base
Answer:
On dissolving in water, a strong base dissociates almost completely and the resulting aqueous solution contains mainly OH ions and the concerned basic radicals, e.g. NaOH, KOH, Ca(OH)₂, Na₂O.

Question 6.
Weak Base
Answer:
On dissolving in water, a weak base does not dissociate completely and the resulting aqueous solution contains a small proportion of OH ions and the concerned basic radical along with a large proportion of undissociated molecules of the base. e.g. NH₄ OH.

Question 7.
Alkali
Answer:
The bases which are highly soluble in water are called alkali, e.g. NaOH, KOH, NH3. Here, NaOH and KOH are strong alkalis while NH₃ is a weak alkali.

Question 8.
Basicity of acids
Answer:
The number of H⁺ ions obtainable by the dissociation of one molecule of an acid is called its basicity.

Question 9.
Acidity of bases
Answer:
The number of OH ions obtainable by the dissociation of one molecule of a base is called its acidity.

Question 10.
Concentration of solute in the solution.
Answer:
The proportion of a solute in a solution is called the concentration of the solute in the solution.

Question 11.
Concentrated solution.
Answer:
When the concentration of a solute in its solution is high, it is a concentrated solution.

Question 12.
Dilute solution
Answer:
When the concentration of a solute in its solution is low, it is a dilute solution.

Question 13.
Neutralization
Answer:
A reaction in which an acid reacts with a base to form salt and water is called a neutalization reaction.
NaOH + HC1 → NaCl + H₂O
Base + Acid → Salt + Water

Question 14.
Cathode
Answer:
The electrode connected to the negative terminal of a battery by means of a conducting wire is called a cathode.

Question 15.
Anode
Answer:
The electrode connected to the positive terminal of a battery by means of a conducting wire is called an anode.

Question 16.
Cations
Answer:
Cations are positively charged ions which are attracted towards negative electrode (cathode) when electricity is passed into a solution of an ionic compound.

Question 17.
Anions
Answer:
Anions are negatively charged ions which are attracted towards the positive electrode (anode) when electricity is passed into a solution of an ionic compound.

Question 18.
Electrolytic cell
Answer:
An assembly that consists of a container with an electrolyte and the electrodes dipped in it, is called an electrolytic cell.

Question 19.
Molarity of a solution
Answer:
The number of moles of the solute dissolved in one litre of the solution is called the molarity of that solution. The molarity of a solute is indicated by writing its molecular formula inside a square bracket for example [NaCl] = 1

Question 20.
Acid – base indicators
Answer:
Some natural and synthetic dyes show two different colours in acidic and basic solution, and such dyes are acid base indicators.

Explain the following chemical reactions with the help of balanced equations:

Question 1.
Magnesium reacts with dilute hydrochloric acid.
Answer:
When magnesium reacts with dilute hydrochloric acid, it forms magnesium chloride and hydrogen gas is liberated.

Question 2.
When copper reacts with nitric acid.
Answer:
When copper reacts with nitric acid, it forms copper nitrate and hydrogen gas is liberated.

Question 3.
When ferric oxide reacts with diluted hydrochloric acid.
Answer:
When Ferric oxide reacts with diluted hydrochloric acid, it forms ferric chloride and water.

Question 4.
When calcium oxide reacts with dilute hydrochloric acid.
Answer:
When calcium oxide reacts with dilute hydrochloric acid, it forms calcium chloride and water.

Question 5.
When Magnesium oxide reacts with dilute hydrochloric acid.
Answer:
When magnesium oxide reacts with dilute hydrochloric acid, it forms magnesium chloride and water.

Question 6.
When zinc oxide reacts with dilute hydrochloric acid.
Answer:
When zinc oxide reacts with dilute hydrochloric acid, it forms zinc chloride and water.

Question 7.
When aluminium oxide reacts with hydrogen fluoride
Answer:
When aluminium oxide reacts with hydrogen fluoride, it forms Aluminium fluoride arid water.

Question 8.
When carbon dioxide reacts with sodium hydroxide.
Answer:
When carbon dioxide reacts with Sodium hydroxide, it forms Sodium carbonate and water.

Question 9.
When carbon dioxide reacts with potassium hydroxide.
Answer:
When carbon dioxide reacts with potassium hydroxide, it forms potassium carbonate and water.

Question 10.
When sulphur trioxide reacts with sodium hydroxide.
Answer:
When sulphur trioxide reacts with sodium hydroxide, it forms sodium sulphate and water.

Question 11.
When calcium hydroxide reacts with carbon dioxide.
Answer:
When calcium hydroxide reacts with carbon dioxide, it forms calcium carbonate and water.

Question 12.
When sodium carbonate reacts with hydrochloric acid.
Answer:
When sodium carbonate reacts with hydrochloric acid, it forms sodium chloride, carbon dioxide and water.

Question 13.
When sodium carbonate reacts with sulphuric acid.
Answer:
When sodium carbonate reacts with sulphuric acid, it forms sodium sulphate, carbon dioxide and water.

Question 14.
When calcium carbonate reacts with nitric acid.
Answer:
When calcium carbonate reacts with nitric acid, it forms calcium nitrate, carbon dioxide and water.

Question 15.
When potassium carbonate reacts with sulphuric acid.
Answer:
When potassium carbonate reacts with sulphuric acid, it forms potassium sulphate, carbon dioxide and water.

Question 16.
When sodium bicarbonate reacts with hydrochloric acid. OR Dilute HC1 was poured on baking soda
Answer:
When sodium bicarbonate reacts with hydrochloric acid, it forms sodium chloride, carbon dioxide and water.

Question 17.
When potassium bicarbonate reacts with nitric acid.
Answer:
When potassium bicarbonate reacts with nitric acid, it forms potassium nitrate, carbon dioxide and water.

Question 18.
When sodium bicarbonate reacts with acetic acid.
Answer:
When sodium bicarbonate reacts with acetic acid, it forms sodium acetate, carbon dioxide and water.

Question 19.
When copper sulphate is heated.
Answer:
When copper sulphate is heated it loses it’s water of crystallization to form white anhydrous copper sulphate.

Question 20.
When Ferrous sulphate is heated.
Answer:
When ferrous sulphate is heated it loses its water of crystallization to form white anhydrous ferrous sulphate.

Q.2. (B)-3. Complete the following table.

Question 1.
Complete the following table.
Answer:

Complete the following reactions.

Question 1.
Answer:

Question 2.
Metal + Dilute acid → Salt + Hydrogen
Answer:

Question 3.
Metal oxide + Dilute acid → SaIt + Water
Answer:

Question 4.
Oxide of non-metal + base → salt + water
Answer:

Question 5.
Carbonate salt of metal + dilute acid → Another salt of metal + Carbon dioxide + water
Answer:

Question 6.
Bicarbonate salt of metal + dilute acid → Another salt of metal + carbon dioxide + water
Answer:

Give scientific reasons:

Question 1.
Ionic compound NaCl has very high stability.
Answer:

• The outermost shell of both Na⁺ and Cl^– ions is a complete octet.
• An electronic configuration with a complete octet indicates a stable state.
• A molecule of NaCl has Na⁺ and Cl^– ions. An ionic bond is formed between these ions.
• The force of attraction between them is very strong as it is formed between the oppositely charged Na⁺ and Cl^– ions.
• Therefore NaCl, an ionic compound has very high stability.

Question 2.
Ionic compound dissociates while forming an aqueous solution.
Answer:

• On dissolving in water, an ionic compound forms an aqueous solution.
• In the solid state, the oppositely charged ions in the ionic compound are sitting side by side.
• When an ionic compound being to dissolve in water, the water molecules push themselves in between the ions of the compound and it separates them from each other, that is to say, an ionic compound dissociates while forming an aqueous solution.

Question 3.
Blue coloured copper sulphate crystals become colourless on heating.
Answer:

• Copper sulphate crystals are blue in colour and crystalline in form due to presence of water of crystallisation.
• Each molecule of crystalline copper sulphate contains five molecules of water of crystallisation (CuSO₄.5H₂O).
• On heating, the copper sulphate crystals lose the water of crystallisation and turns into white amorphous powder called as anhydrous copper sulphate.
• Therefore, blue coloured copper sulphate crystals become colourless on heating.

Question 4.
During electrolysis of water, a few drops of sulphuric acid are added to it.
Answer:

• Pure water is a covalent compound and hence it is a non-electrolyte and does not conduct electricity.
• When a few drops of sulphuric acid (H₂SO₄) are added to water.
• Being a strong acid it dissociates almost completely in its solution forming H⁺ cations and \(\mathrm{SO}_{4}^{2-}\) anions.
• The movement of these ions in the solution towards the respective electrodes amount to the conduction of electricity through the solution.
• Therefore, during electrolysis of water, a few drops of sulphuric acid are added to it.

Question 5.
Glucose is a non-electrolyte.
Answer:

• Glucose is a covalent compound
• It does not form any ions in its aqueous solution.
• Due to this aqueous solution of glucose does not conduct electronic current.
• Hence, glucose is a non-electrolyte.

Question 6.
Pure water is a poor conductor of electricity but aqueous solution of sodium chloride conducts electricity.
Answer:

• Pure water does not contain any free ions.
• Sodium chloride (NaCl) is an ionic compound made up of sodium cation (Na⁺) and chloride anion (Cl)
• When sodium chloride is dissolved in water , these ions dissociates in its aqueous solution. ‘
• These ions are free to move in the solution and conduct electricity.
• Therefore, pure water is a poor conductor of electricity but aqueous solution of sodium Chloride conducts electricity.

Question 7.
When carbon dioxide gas is passed through freshly prepared lime water, the limewater turns milky.
Answer:

• Limewater traditionally means a weak solution of the alkali calcium hydroxide Ca(OH)₂.
• When CO₂ is passed through limewater, it reacts with calcium hydroxide to form insoluble particulates (precipitate of calcium carbonate (CaCO₃).
• Calcium carbonate is weak basic salt and this gives a milky white precipitate.
  
• Hence, lime water turns milky when CO₂ gas is passed through it.

Q.3.1. Answer the following:

Question 1.
Write down chemical equations for
(a) Zinc oxide reacts with sodium hydroxide
(b) Aluminium oxide reacts with sodium hydroxide.
Answer:
(a) When zinc oxide reacts with sodium hydroxide, it forms sodium zincate and water

(b) When Aluminium oxide reacts with sodium hydroxide, it forms sodium aluminate and water.

Question 2.
Can we call Al₂O₃ and ZnO acidic oxides on the basis of above reactions.
Answer:

• No, because they also react with acids to form their respective salts and water.
• So, they show the properties of basic oxides also.

Question 3.
Define ‘amphoteric oxides’ and give two examples.
Answer:

• Amphoteric oxides are those oxides which react with both adds as well as bases to form their respective salts and water.
• Amphoteric oxides show the properties of both acidic oxides as well as basic oxides. ZnO and Al₂ O₃ are amphoteric oxides.?

Question 4.
Take a solution of 1g copper sulphate in 50ml water in a 100 ml capacity beaker. Use a thick plate of copper as anode and a carbon rod as cathode. Arrange the apparatus as shown in the figure and pass an electric current through the circuit for some time. Do you see any changes?
Answer:

• A thin film of copper metal is deposited on cathode which is immersed in solution. There is no change in colour of solution
• The electrons from cathode combines with Cu²⁺ ion from the solution forming Cu atoms which were then deposited on the cathode.

Q.3.5. Answer in brief:

Question 1.
What are acids, bases and salts?
Answer:

• Compounds having H⁺ as the basic radical in their molecules are called Acids.
• Compounds having OH^– as the acidic radical in their molecule are called Bases.
• Ionic compounds which have a basic radical other than H⁺ and an acidic radical other than OH^– are called salts.

Question 2.
What is an ionic bond?
Answer:

• The molecule of an ionic compound has two constituents namely cation (positive ion / basic radical) and anion (negative ion / acidic radical).
• There is a force of attraction between these ions as they are oppositely charged, and that is called the ionic bond.
• The force of attraction between one positive charge on a cation and one negative charge on an anion makes one ionic bond.

Question 3.
Give examples to show that proportions of H⁺ and OH^– ions in aqueous solution determines the properties of those solutions.
Answer:
The examples to show that proportions of H⁺ and OH^– ions in aqueous solution determines the properties of those solutions are :

• The proportions of H⁺ and OH ions divides soil into the acidic, neutral and basic, types of soil.
• It is necessary for blood, cell sap etc to have H⁺ and OH^– ions in certain definite proportions for their proper functioning.
• Fermentation carried out with the help of micro-organisms, other biochemical processes and also many chemical processes require the proportion of H⁺ and OH^– ions to be maintained within certain limits.

Question 4.
What is pH scale?
Answer:

1. In 1909, the Danish scientist Sorensen introduced a convenient new scale of expressing H⁺ ion concentration which is found to be useful in chemical and biochemical processes.
2. It is the pH scale (pH: power of hydrogen). The pH scale extends from 0 to 14. According to this scale pure water has a pH of 7. pH 7 indicates a neutral solution. This pH is the midpoint of the scale.
3. The pH of an acidic solution is less than 7 and?

Question 5.
Give the pH of following solutions.
Answer:

Question 6.
What is universal indicator? Which is the most accurate method of measuring the pH of a solution?
Answer:

• In the pH scale, the pH of solutions varies from 0 to 14 in accordance with the strength of the acid or base.
• To show these variations in pH, a universal indicator is used.
• A universal indicator shows different colours at different values of pH. A universal indicator is made by mixing several synthetic indicators in specific proportions.
• The pH of a solution can be determined by means of a universal indicator solution or the pH paper made from it.
• However, the most accurate method of measuring the pH of a solution is to use an electrical instrument called pH meter.
• In this method, pH is measured by dipping electrodes into the solution.

Answer in detail:

Question 1.
Explain the Arrhenius theory of acids and bases.
Answer:
The Swedish scientist Arrhenius put forth a theory of acids and bases in the year 1887. This theory gives definitions of acids and bases as follows:
Acid : An acid is a substance which on dissolving in water gives rise to H ion as the only cation. For example, HCl, H₂SO₄, H₂CO₃

Base: Abase is a substance which on dissolving in water gives rise to the OH ion as the only anion, For example, NaOH, Ca(OH)₂

Question 2.
Write a short note on Neutralization.
Answer:

• Take 10 ml of dilute HCl in a beaker, go on adding dilute NaOH drop by drop and record the pH.
• Stop adding the NaOH when the green colour appears on the pH paper, that is when the pH of solution becomes 7.
• Both HCl and NaOH dissociate in their aqueous solutions.
• Addition of NaOH to HCl solution is like adding a large concentration of OH ions to a large concentration of H⁺ ions.
• However water dissociates into H⁺ and OH ions to a very small extent.
• Therefore on mixing the excess OH^– ions combines with excess H⁺ ions and forms H₂O molecules which mix with solvent water.
• This change can be represented by the ionic equation shown as follows. H⁺ + Cl^– + Na⁺ + OH^– → Na⁺ + Cl^– + H₂O
• It can be observed that Na⁺ and CT ions are there on both the sides. Therefore the net ionic reaction is H⁺ + OH^– → H₂O
• As NaOH solution is added drop by drop to the HCl solution, the concentration of ff goes on decreasing due to combination with added OH ions, and that is how the pH goes on increasing.
• When enough NaOH is added to HCl, the resulting aqueous solution contains only Na⁺ and Cl^– ions, that is, NaCl, a salt, and the solvent water. The only source of H⁺ and OH^– ions in this solution is a dissociation of water.
• Therefore, this reaction is called the Neutralization reaction. The Neutralization reaction is also represented by the following simple equation.
  

Question 3.
Explain the water of Crystallization.
Answer:

• Take some crystals of blue vitriol (CuSO₄. 5H₂O) in a test tube. Heat the test tube on a low flame of a burner.
• It was observed that on heating, the crystalline structure of blue vitriol broke down to form a colourless powder and water came out.
• This water was part of the crystal structure of blue vitriol. It is called water of crystallization.
• On adding water to the white powder a solution
  
  was formed which had the same colour as the solution in the first test tube.
• From this we come to know that no chemical change has occurred in the crystals of blue vitriol due to heating.
• Losing water on heating blue vitriol, breaking down of the crystal structure, losing blue colour and regaining blue colour on adding water are all physical changes.
  
• Similarly, ferrous Sulphate crystals also contain 7 molecules of water of crystallization which are lost on heating.
• The reaction is represented as
  
• Ionic compounds are crystalline in nature. These crystals are formed as a result of definite arrangement of ions.
• In the crystals of some compounds, water molecules are also included in this arrangement.
• That is the water of crystallization. The water of crystallization is present in a definite proportion of the chemical formula of the compound.

Question 4.
Explain the conduction of electricity through solutions of ionic compounds
Answer:

1. Electrons conduct electricity through electrical wires, and ions conduct electricity through a liquid or a solution.
2. Electrons leave the battery at the negative terminal, complete the electric circuit and enter the battery at the positive terminal.
3. When there is a liquid or a solution in the circuit, two rods, wires or plates are immersed in it. These are called electrodes.
4. Electrodes are made of conducting solid. The electrode connected to negative terminal of a battery by means of a conducting wire is called a cathode and the electrode connected to the positive terminal of a battery is called anode.
5. We have seen that salts, strong acids and strong bases dissociates almost completely in their aqueous solutions.
6. Therefore the aqueous solutions of all these three contain large number of cations and anions.
7. A characteristic of liquid state is the mobility of its particles. Due to its mobility the positive charged ions of the solution are attracted to the negative electrode or cathode.
8. On the other hand, the negative charged ions of the solution are attracted to the positive electrode or anode.
9. The movement of ions in the solution towards the respective electrodes accounts to the conduction of electricity through the solution.
10. From this we can understand that those liquids or solutions which contain a large number of dissociated ions conduct electricity.
    

 

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 6 Classification of Plants Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 6 Classification of Plants

Class 9 Science Chapter 6 Classification of Plants Textbook Questions and Answers

1. Match the proper terms from columns A and C with the description in column B.

2. Complete the sentences by filling in the blanks and explain those statements.
(angiosperms, gymnosperms, spore, Bryophyta, thallophyta, zygote)
a. ……………….. plants have soft and fiber-like body.

b. ……………….. is called the ‘amphibian’ of the plant kingdom.
Answer:
Bryophyta plant is called the ‘amphibian’ of the plant kingdom

c. In pteridophytes, asexual reproduction occurs by ……………….. formation and sexual reproduction occurs by ………………..formation.
Answer:
Spore, zygote: Pteridophyta plants show alteration of generation. One generation reproduces by spore-formation and the next generation reproduces sexually by zygote formation.

d. Male and female flowers of ……………….. are borne on different sporophylls of the same plant.
Answer:
Gymnosperms bear their male and female flowers on different sporophylls of the same plant

3. Answer the following questions in your own words.

a. Write the characteristics of subkingdom Phanerogams.
Answer:

• Plants which have special structures for reproduction and produce seeds are called Phanerogams.
• In these plants, after the process of reproduction, seeds are formed which contain the embryo and stored food.
• During the germination of the seed, the stored food is used for the initial growth of the embryo.
• Depending upon whether seeds are enclosed in a fruit or not phanerogams are classified into gymnosperms and angiosperms.

b. Distinguish between monocots and dicots.
Answer:

	Dicots	Monocots
Seed	Two cotyledons	Single cotyledon
Root	Well developed, primary root (Taproot)	Fibrous roots
Stem	Strong, hard. e.g. Banyan tree	Hollow, e.g. Bamboo False, e.g. Banana Disc-like, e.g. Onion.
Leaf	Reticulate venation	Parallel venation
Flower	Flowers with 4 or 5 parts or in their multiples (tetramerous or pentamerous)	Flowers with 3 parts or in multiples of three (trimerous).

c. Write a paragraph in your own words about the ornamental plants called ferns.
Answer:

• Ferns belong to the group of plants called Pteridophyta.
• They have well-developed roots, stem and leaves but do not bear flowers and fruits.
• They have separate tissues for the conduction of food and water.
• They reproduce with the help of spores formed along the back or posterior surface of their leaves.
• They reproduce asexually by spore formation and sexually by zygote formation.

d. Sketch, label and describe the Spirogyra.

e. Write the characteristics of the plants belonging to division Bryophyta.
Answer:

• Bryophyta group of plants are called the amphibians of the plant kingdom because they grow in moist soil but need water for reproduction.
• These plants are thalloid, multicellular and autotrophic.
• They reproduce by spore-formation.
• Their plant body structure is flat, ribbon-like, long, without true roots, stem and leaves.
• Instead, they have stem-like or leaf-like parts and root-like rhizoids.
• They do not have specific tissues for the conduction of food and water.
• Examples: Moss (Funaria), Anthoceros, Riccia etc.?

4. Sketch and label the figures of the following plants and explain them into brief.
Marchantia, Funaria, Fern, Spirogyra.

Question 1.
Spirogyra.
Answer:

• Spirogyra belongs to the division thallophyta. They are called as algae.
• It grows mainly in water.
• It does not have specific parts like root-stem- leaves-flowers but are autotrophic due to the presence of chlorophyll.
• The plant body of Spirogyra is soft and fibre-like.
• It has spirally arranged chloroplasts in its cell.

Question 2.
Funaria and Marchantia (Bryophyta)
Answer:

• These plants are called ‘amphibians’ of the plant kingdom because they grow mostly in soil and need water for reproduction.
• They do not have specific tissues for the conduction of food and water.
• The plant body is fiat, ribbon-like long, without true roots, stem and leaves
• Instead, they have stem-like or leaf-like parts and root like rhizoids.

Question 3.
Fern (Pteridophyta):
Answer:

• They have well-developed roots, stem and leaves for the conduction of food and water.
• They do not bear flowers and fruits.
• They reproduce with the help of spores present along the back or posterior surface of the leaves.

5. Collect a monocot and dicot plant available in your area. Observe the plants carefully and describe them in scientific language.

6. Which criteria are used for the classification of plants? Explain with reasons.
Answer:
Criteria for classification of plants:

• If plants do not bear flowers, fruits and seeds, they are non-seed bearing plants. If they bear flowers, fruit and seeds, they are seed-bearing plants.
• Presence or absence of conducting tissues- Plants such as pteridophytes, gymnosperms and angiosperms which possess conducting tissues are included in vascular plants whereas thallophytes and bryophytes which do not possess conducting tissues are included under non-vascular plants.
• Depending upon whether the seeds are enclosed in fruit or not, plants are classified as gymnosperms (naked-seeds) and angiosperms (seeds covered by fruit)
• Depending upon the number of cotyledons in seeds, plants are classified into dicotyledons and monocotyledons

Class 9 Science Chapter 6 Classification of Plants Intext Questions and Answers

Can you recall?

Question 1.
How have living organisms been classified?
Answer:
(i) Organisms have been classified based on the following:

• Cell structure
• Body Organisation
• Mode of nutrition
• Reproduction

(ii) Organisms are also classified at kingdom level and groups and subgroups.

Activity-based questions

Question 1.
You may have seen a lush green soft carpet on old walls, bricks and rocks in the rainy season. Scrape it gently with a small ruler, observe it under a magnifying lens and discuss.
Answer:

• It shows considerable tissue complexity and is differentiated into two main parts: a root and a shoot.
• They have a variety of specialized tissues within these two regions of the body.
• Same kind of cells are seen throughout the whole body except reproductive cells.

Question 2.
You may have seen ferns among the ornamental plants in a garden. Take a leaf of a fully grown fern and observe it carefully.
Answer:

• New leaves typically expand by the unrolling in a tight spiral manner.
• The anatomy of fern leaves can either be simple or highly divided.
• They show the presence of spores formed along the back or posterior surface of their leaves.

Question 3.
Observe all garden plants like Cycas, Christmas tree, Hibiscus, Lily, etc. and compare them. Note the similarities and differences among them. Which differences did you notice in gymnosperms and angiosperms?
Answer:
Cycas and Christmas tree are gymnosperms, whereas Hibiscus and lily are angiosperms.

1. Similarities: These plants have special structures for reproduction and produce seeds. During the germination of the seed, the stored food is used for the initial growth of the embryo.
2. Differences: In gymnosperms, reproductive organs have cones whereas in angiosperms reproductive organs have flowers.
3. In gymnosperms, seeds are without natural coverings whereas in angiosperms seeds are enclosed in natural coverings called fruits.

Question 4.
Soak the seeds of corns, beans, groundnut, tamarind, mango, wheat, etc. in water for 8 to 10 hrs. After they are soaked, check each seed to see whether it divides into two equal halves or not and categorize them accordingly.
Answer:
Monocots: com, wheat (it cannot be divided into equal halves)
Dicots: beans, groundnut, tamarind and mango (it can be divided into two equal halves)

Class 9 Science Chapter 6 Classification of Plants Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
The five-kingdom classification was proposed b7
(a) Robert Whittaker
(b) Robert Hooke
(c) Eichler
(d) Louis Pasteur
Answer:
(a) Robert Whittaker

Question 2.
In 1883, classified plants into two sub-kingdoms.
(a) Robert Whittaker
(b) Alexander Fleming
(c) Eichler
(d) Robert Hooke
Answer:
(c) Eichler

Question 3.
Ulothrix, ulva, sargassum belong to
(a) Bryophyta
(b) Thallophyta
(c) Pteridophyta
(d) Gymnosperms
Answer:
(b) Thallophyta

Question 4.
is a bryophyte.
(a) Ulva
(b) Nephrolepis
(c) Funaria
(d) Equisetum
Answer:
(c) Funaria

Question 5.
In the seeds are naked.
(a) Pteridophyta
(b) Angiosperms
(c) Gymnosperms
(d) Bryophyta
Answer:
(c) Gymnosperms

Question 6.
In the flowers are reproductive organs.
(a) Angiosperms
(b) Gymnosperms
(c) Pteridophyta
(d) Bryophyta
Answer:
(a) Angiosperms

Question 7.
In the flowers are tetramerous or pentamerous.
(a) Monocotyledons
(b) Dicotyledons
(c) Gymnosperms
(d) Pteridophyta
Answer:
(b) Dicotyledons

Question 8.
In monocotyledonous plants, the stem is
(a) hollow
(b) false
(c) disc-like
(d) all of these.
Answer:
(d) all of these

Question 9.
Lycopodium belongs to
(a) Thallophyta
(b) Bryophyta
(c) Gymnosperms
(d) Pteridophyta
Answer:
(d) Pteridophyta

Question 10.
Leaves of show reticulate venation.
(a) Bamboo
(b) Banana
(c) Onion
(d) Banyan
Answer:
(d) Banyan

Question 11.
Various types of fungi like yeasts and moulds are included in the group
(a) Thallophyta
(b) Halophyte
(c) Xenophyta
(d) Angiosperms
Answer:
(a) Thallophyta

Question 12.
Bryophytes have a root-like structure called
(a) Nodes
(b) Rhizoids
(c) Nodules
(d) Aerenchyma
Answer:
(b) Rhizoids

Question 13.
reproduce with the help of spores formed along the back or posterior surface of their leaves.
(a) Halophyta
(b) Pteridophyta
(c) Thallophyta
(d) Angiosperms
Answer:
(b) Pteridophyta

Question 14.
In ……………………….., the reproductive organs cannot be seen.
(a) Pteridophyta
(b) Cryptogams
(c) Thallophyta
(d) Angiosperms
Answer:
(b) Cryptogams

Question 15.
are mostly evergreen, perennial and woody.
(a) Pteridophyta
(b) Thallophyta
(c) Gymnosperms
(d) Angiosperms
Answer:
(c) Gymnosperms

Question 16.
Gymnosperms bear male and female flowers on different of the same plant.
(a) Branches
(b) Roots
(c) Sporophylls
(d) Flowers
Answer:
(c) Sporophylls

Question 17.
In the seeds are not enclosed by fruit.
(a) Pteridophyta
(b) Thallophyta
(c) Gymnosperms
(d) Angiosperms
Answer:
(c) Gymnosperms

Question 18.
In the seeds are enclosed by fruit.
(a) Pteridophyta
(b) Thallophyta
(c) Gymnosperms
(d) Angiosperms
Answer:
(d) Angiosperms

Question 19.
The plants whose seeds cannot be divided into equal parts are called
(a) Algae
(b) Fungus
(c) Dicotyledons
(d) Monocotyledons
Answer:
(d) Monocotyledons

Question 20
The plants whose seeds can be divided into equal parts are called
(a) Algae
(b) Fungus
(c) Dicotyledons
(d) Monocotyledons
Answer:
(c) Dicotyledons

Find the odd one out:

Question 1.
Ulothrix, Ulva, Nephrolepis, Sargassum
Answer:
Nephrolepis: It belongs to division Pteridophyta whereas the others belong to division thallophyta.

Question 2.
Funaria, Marchantia, Anthoceros, Spirogyra
Answer:
Spirogyra:

Question 3.
Marsilea, Pteris, Lycopodium, Riccia
Answer:
Riccia:

Question 4.
Cycas, Mango, Apple, Banyan
Answer:
Cycas:

Question 5.
Onion, Papaya, Wheat, Green peas
Answer:
Green peas:

Complete the analogy:

(1) Spirogyra : Thallophyta : : Riccia :
(2) Moss : Bryophyta : : Selaginella :
(3) Nephrolepis : Pteridophyta :: Ulothrix :
(4) Pteridophyta : Roots :: Bryophyta :
(5) Gymnosperms : naked seeds : : Angiosperms :
(6) Dicotyledon : Reticulate venation : : Monocotyledon:
(7) Bamboo stem: Hollow:: Onion Stem:
(8) Monocotylendon : Tap root:: Dicotyledon :
Answer:
(1) Bryophyta
(2) Pteridophyta
(3) Thallophyta
(4) Rhizoids
(5) Covered seeds
(6) Parallel venation
(7) Disc like
(8) Fibrous roots

Difference between:

Question 1.
Thallophyta and Bryophyta
Answer:

Thallophyta	Bryophyta
These plants grow mainly in water	They grow in moist soil but need water for reproduction

Question 2.
Gymnosperms and Angiosperms
Answer:

Gymnosperms	Angiosperms
No natural covering on seeds	Seeds are formed in fruits

Question 3.
Algae and Moss
Answer:

Algae	Moss
These plants mainly grow in water.	These plants need water for reproduction.

State whether the following statements are true or false. Correct the false statements:

(1) Thallophyta are called as the amphibians of the plant kingdom.
(2) Fungi like yeasts and moulds are included in division bryophyta.
(3) Moss (Funaria) belongs to division bryophyta.
(4) Bryophyta have specific tissues for conduction of food and water.
(5) Plants belonging to Thallophyta group are only unicellular.
(6) Pteridophytes have well developed roots, stems and leaves.
(7) Pteridophytes reproduce with the help of spores formed along the back or posterior surface of their leaves.
(8) Nephrolepis belongs to division Pteridophyta.
(9) Depending upon whether seeds are enclosed in a fruit or not, phanerogams are classified into monocots and dicots.
(10) Gymnosperms are mostly evergreen, perennial and woody.
(11) Gymnosperms bear male and female flowers on different sporophylls of different plants.
(12) In Angiosperms, the seeds are covered by fruits.
(13) Dicotyledonous plants show reticulate venation.
(14) Moncotyledonous plants have trimerous flowers.
(15) In dicotyledonous plants, the stem is strong and hard.
Answer:
(1) False. Thallophyta plants grow mainly in water.
(2) False. Fungi like yeasts and moulds are included in division thallophyta.
(3) True
(4) False. Bryophyta do not have specialised tissuesfor conduction of food and water.
(5) False. Plants belonging to thallophyta group may be unicellular or multicellular.
(6) True
(7) True
(8) True
(9) False. Depending whether seeds are enclosed in. a fruit or not, angiosperms are classified into monocots and dicots.
(10) True
(11) False. Gymnosperms bear male and female flowers on different sporophylls of the same plant.
(12) True
(13) False. Dicotyledonous plants show parallel venation.
(14) True
(15) True.

Give name

Question 1.
What are ornamental plants are called?
Answer:
Ferns

Question 2.
Plants with two cotyledons are called.
Answer:
Dicots

Question 3.
Plants with single cotyledon are called.
Answer:
Monocots

Question 4.
Type of venation showed by hibiscus plant leaves
Answer:
Reticulate venation

Question 5.
Type of venation showed by lily plant leaves
Answer:
Parallel venation

One line answers

Question 1.
Which plants are mostly evergreen, perennial and woody?
Answer:
Gymnosperms are mostly evergreen, perennial and woody.

Question 2.
Which type of venation showed by dicot plants?
Answer:
Leaves of dicot plants show reticulated venation.

Question 3.
Which type of venation showed by monocot plants?
Answer:
Leaves of monocot plants show parallel venation

Question 4.
How are angiosperms classified into monocot and dicot?
Answer:
Depending whether seeds and enclosed in fruit or not, angiosperms are classified into monocot and dicot

Question 5.
In which division are fungi like moulds and yeast classified?
Answer:
Fungi like moulds and yeast classified in division thallophyta.

Question 6.
Plants belonging to which group may be unicellular or multicellular?
Answer:
Plants belonging to thallophyta group may be unicellular or multicellular

Give scientific reason

Question 1.
Thallophyta plants have thin and fibre like body
Answer:
Thallophyta: These plants grow mainly in water i.e. fresh water as well as in saline water, therefore they usually have a soft and fibre-like (filamentous) body.

Question 2.
Bryophyta plants are called the amphibian plants.
Answer:
Bryophyta: They grow in moist soil but need water for reproduction. Therefore, they are called ‘amphibians of plant kingdom’.

Question 3.
Gymnosperms bear their male and female flowers on different sporophylls of the same plant
Answer:
Gymnosperms: As these plants do not take the assistance of pollinators i.e. vectors, the male and female flowers are present on the different sporophyll of the same plant for successful fertilisation.

Write note on

Question 1.
August W. Eichler
Answer:
In 1883, Eichler, a botanist, classified the Kingdom Plantae into two subkingdoms. As a result, two subkingdoms, cryptogams and phanerogams were considered for plant classification.

Question 2.
Thallophyta
Answer:
These plants grow mainly in water. This group of plants, which do not have specific parts like root-stem-leaves-flowers but are autotrophic due to the presence of chlorophyll, is called algae. Algae show great diversity. They may be unicellular or multicellular, and microscopic or large. Examples of algae are Spirogyra, Ulothrix, Ulva, Sargassum, etc. Some of these are found in fresh water while some are found in saline water. These plants usually have a soft and fibre-like body. Various types of fungi like yeasts and moulds which do not have chlorophyll are also included in this group.

Question 3.
Bryophyta
Answer:
This group of plants is called the amphibians’ of the plant kingdom because they grow in moist soil but need water for reproduction. These plants are thalloid, multicellular and autotrophic. They reproduce by spore formation. The structure of the plant body of bryophytes is flat, ribbon-like long, without true roots, stem and leaves. Instead, they have stem-like or leaf-like parts and root-like rhizoids. They do not have specific tissues for conduction of food and water. Examples are Moss (Funaria), Marchantia, Anthoceros, Riccia, etc.

Question 4.
Pteridophyta
Answer:
Plants from this group have well developed roots, stem and leaves and separate tissues for conduction of food and water. But, they do not bear flowers and fruits. They reproduce with the help of spores formed along the back or posterior surface of their leaves. Examples are ferns like Nephrolepis, Marsilea, Pteris, Adiantum, Equisetum, Selaginella, Lycopodium, etc. These plants reproduce asexually by spore-formation and sexually by zygote formation. They have a well-developed conducting system.

Question 5.
Phanerogams
Answer:
Plants which have special structures for reproduction and produce seeds are called phanerogams. In these plants, after the process of reproduction, seeds are formed which contain the embryo and stored food. During germination of the seed, the stored food is used for the initial growth of the embryo. Depending upon whether seeds are enclosed in a fruit or not, phanerogams are classified into gymnosperms and angiosperms.

Question 6.
Gymnosperms
Answer:
Gymnosperms are mostly evergreen, perennial and woody. Their stems are without branches. The leaves form a crown. These plants bear male and female flowers on different sporophylls of the same plant. Seeds of these plants do not have natural coverings, i.e. these plants do not form fruits and are therefore called gymnosperms. (gymnos: naked, sperms: seeds). Examples Cycas, Picea (Christmas tree), Thuja (Morpankhi), Pinus (Deodar), etc.

Question 7.
Angiosperms
Answer:
The flowers these plants bear are their reproductive organs. Flowers develop into fruits and seeds are formed within fruits. Thus, these seeds are covered; hence, they are called angiosperms (angios: cover, sperms: seeds). The plants whose seeds can be divided into two equal halves or dicotyledons are called dicotyledonous plants and those whose seeds cannot be divided into equal parts are called monocotyledonous plants.

Complete the flow chart.

Question 1.
Living Organisms

Answer:

Question 2.
Kingdom: Plantae

Answer:

Distinguish between:

Question 1.
Bryophyta and Pteridophyta:
Answer:

Bryophyta	Pteridophyta
Bryophytes grow in soil but need water for reproduction.	Pteridophytes grow in soil.
Plant body is without specific parts like true roots, stem and leaves.	Plant body is differentiated into true roots, stem and leaves.
Conducting tissues for food and water absent.	Conducting tissues for food and water present.
Examples: Moss (Funaria), Marchantia, Anthoceros, etc.	Examples: Nephrolepis, Marsilea, Pteris, Adiantum, Lycopodium etc.

Question 2.
Angiosperms and Gymnosperms.
Answer:

Angiosperms	Gymnosperms
(i) In Angiosperms, the stems have branches.	(i) In Gymnosperms, the stems are without branches.
(ii) Reproductive organs are flowers.	(ii) Reprodcutive organs are cones.
(iii) Seeds are enclosed in natural coverings, i.e., fruits.	(iii) Seeds are not enclosed in natural coverings.
(iv) Examples: Mango, Bamboo, etc.	(iv) Examples: Cycas, Picea etc.

Question 3.
Cryptogams and Phanerogams.
Answer:

Cryptogams	Phanerogams
(iii) Their reproductive organs are hidden.	(iii) Their reproductive organs are exposed.
(iii) They reproduce by forming spores.	(iii) They reproduce by forming seeds.
(iii) They are less evolved plants.	(iii) They are highly evolved plants.
(iv) They are divided into Thallophyta,	(iv) They are divided into Gymnosperms and
Bryophyta, Pteridophyta.	Angiosperms.

Distinguish between:

Question 1.
Thallophyta
Answer:
Spirogvra, Ulothrix, Ulva, Sargassum

Question 2.
Bryophyta
Answer:
Moss (Funaria), Marchantia, Anthoceros, Riccia

Question 3.
Pteridophyta
Answer:
Nephrolepis, Marsilea, Pteris, Adiantum, Equisetum, Selaginella, Lycopodium

Question 4.
Gymnosperms
Answer:
Cycas, Picca (Christmas tree), Thuja (Morpankhi), Pinus (Deodar)

Question 5.
Angiosperms
Answer:
Tamarind, Mango, Apple, Lemon

Question 6.
Monocot plants
Answer:
Bamboo, bananas, corn, daffodils, garlic, ginger, grass, lilies, onions, orchids, rice, sugarcane, tulips, and wheat

Question 7.
Dicot plants
Answer:
Rose, sunflower, grapes, strawberries, tomatoes, peas, peanuts and potatoes

Observe the figure and answer the questions

1. Dicot Plants

Question 1.
What are the characteristics of the above plants in terms of root system?
Answer:
Well developed, primary root (Tap root)

Question 2.
What are the characteristics of the above plants in terms of flowers?
Answer:
Flowers with 4 or 5 parts or in their multiples (tetramerous or pentamerous)

Question 3.
What are the characteristics of the above plants in terms of leaf venations?
Answer:
Reticulate Venation

Question 4.
What are the characteristics of the above plants in terms of type of stem?
Answer:
Strong and hard

Question 5.
What are the characteristics of the above plants in terms of seed?
Answer:
Two cotyledons

Question 6.
Give example of the following types of plants
Answer:
Rose, sunflower, grapes, strawberries, tomatoes, peas, peanuts and potatoes

2. Monocot Plants

Question 1.
What are the characteristics of the above plants in terms of root system?
Answer:
Fibrous roots

Question 2.
What are the characteristics of the above plants in terms of flowers?
Answer:
Flowers with 3 parts or in multiples of three (trimerous).

Question 3.
What are the characteristics of the above plants in terms of leaf venations?
Answer:
Parallel Venation

Question 4.
What are the characteristics of the above plants in terms of type of stem?
Answer:
Hollow, False or Disc-like

Question 5.
What are the characteristics of the above plants in terms of seed?
Answer:
Single cotyledons

Question 6.
Give example of the following types of plants
Answer:
Bamboo, bananas, com, daffodils, garlic, ginger, grass, lilies, onions, orchids, rice, sugarcane, tulips, and wheat

3. Spirogyra

Question 1.
Which division of plants does this plant come under?
Answer:
This plant come under Division I Thallophyta.

Question 2.
Where does this plant grow?
Answer:
These plants grow mainly in water.

Question 3.
Are these types of plants unicellular or multicellular?
Answer:
They may be unicellular or multicellular and microscopic or large.

Question 4.
Are these types of plant autotropic?
Answer:
They are autotrophic due to the presence of chlorophyll but types of fungi like yeasts and moulds which do not have chlorophyll are also included in this group.

Question 5.
Do these plants have a root-stem-leaves-flowers system?
Answer:
They do not have specific parts like root-stem- leaves-flowers.

Question 6.
How is the body of these types of plants?
Answer:
These plants usually have a soft and fibre-like body.

4. Funaria

Question 1.
Which division of plants does this plant come under?
Answer:
This plant come under Division II Bryophyta.

Question 2.
Where does this plant grow?
Answer:
They grow in moist soil but need water for reproduction.

Question 3.
What are these group of plants called in the plant kingdom?
Answer:
This group of plants is called the ‘amphibians’ of the plant kingdom.

Question 4.
Are these types of plant autotropic?
Answer:
They reproduce by spore formation.

Question 5.
Do these plants have root-stem-leaves-flowers system?
Answer:
The structure of the plant body of bryophytes is flat, ribbon-like long, without true roots, stem and leaves.

Question 6.
What do these plants have instead of roots?
Answer:
They have root like rhizoids.

5. Fern

Question 1.
Which division of plants does this plant come? under?
Answer:
This plant come under Division III Pteridophy ta.

Question 2.
Where does this plant grow?
Answer:
They grow in soil.

Question 3.
How do these plants reproduce?
Answer:
These plants reproduce asexually by spore- formation and sexually by zygote formation.

Question 4.
Do these plants produce flowers and fruits?
Answer:
They do not bear flowers and fruits.

Question 5.
Do these plants have root-stem-leaves-flowers system?
Answer:
Plants from this group have well developed roots, stem and leaves and separate tissues for conduction of food and water.

Question 6.
Where are the spores formed in the plants body?
Answer:
The spores formed along the back or posterior surface of their leaves.

6. Cycas

Question 1.
Which division of plants does this plant come under?
Answer:
This plant come under Division III Phanerogams Division I Gymnosperms.

Question 2.
Explain structure of these types of plants?
Answer:
Gymnosperms are mostly evergreen perennial and woody.

Question 3.
How is stem and leaves of these types of plants?
Answer:
Their stems are without branches and the leaves form a crown.

Question 4.
Where are the male and female flowers located?
Answer:
These plants bear male and female flowers on different sporophylls of the same plant.?

Question 6.
Give some examples of these types of plants?
Answer:
Rose, sunflower, grapes, strawberries, tomatoes, peas, peanuts and potatoes

7. Monocot and Dicot plants

Question 1.
Which division of plants does this plant come under?
Answer:
ThisplantcomeunderDivisionlllPhanerogams Division II Angiosperms

Question 2.
How are the seeds of these types of planis?
Answer:
The seeds are formed within fruits thus these seeds are covered

Question 3.
How can we classify the plants according to their seeds in this division?
Answer:
The plants whose seeds can be divided into two equal halves or dicotyledons are called dicotyledonous plants and those whose seeds cannot be divided into equal parts are called monocotyledonous plants.

Question 4.
How the venations are present on the leaves of these types of plants?
Answer:
These plants bear parallel or reticulated venations on the leaves.

Question 5.
How is the root system of these types of plants?
Answer:
The root systems of these types of plant are tap roots or fibrouš roots.

Complete the paragraph

Question 1.
Thallophyta plants grow mainly in …………….. . This group of plants, which do not have specific parts like root-stem-leaves-flowers but are autotrophic due to the presence of …………….., is called algae. Algae show great diversity. They may be unicellular or …………….., and microscopic or large. Examples of algae are Spirogyra, Ulothrix, Ulva, Sargassum, etc. Some of these are found in fresh water while some are found in saline water. These plants usually have a …………….. and fibre-like body. Various types of …………….. like yeasts and moulds which do not have …………….. are also included in this group.
Answer:
Thallophyta plants grow mainly in water. This group of plants, which do not have specific parts like root-stem-leaves-flowers but are autotrophic due to the presence of chlorophyll, is called algae. Algae show great diversity. They may be unicellular or multicellular, and microscopic or large. Examples of algae are Spirogyra, Ulothrix, Ulva, Sargassum, etc. Some of these are found in fresh water while some are found in saline water. These plants usually have a soft and fibre-like body. Various types of fungi like yeasts and moulds which do not have chlorophyll are also included in this group.

Question 2.
…………….. group of plants is called the amphibians’ of the plant kingdom because they grow in moist soil but need …………….. for reproduction. These plants are thalloid, multicellular and autotrophic. They reproduce by …………….. formation. The structure of the plant body of bryophytes is flat, ribbon?like long, without true …………….., stem and leaves. Instead, they have stem-like or leaf?like parts and root-like ……………. . They do not have specific …………….. for conduction of food and water. Examples are Moss (Funaria), Marchantia, Anthoceros, Riccia, etc.
Answer:
Bryophyta group of plants is called the ‘amphibians’ of the plant kingdom because they grow in moist soil but need water for reproduction. These plants are thalloid, multicellular and autotrophic. They reproduce by spore formation. The structure of the plant body of bryophytes is flat, ribbon-like long, without true roots, stem and leaves. Instead, they have stem-like or leaf-like parts and root-like rhizoids. They do not have specific tissues for conduction of food and water. Examples are Moss (Funaria), Marchantia, Anthoceros, Riccia, etc.

Question 3.
Plants from Pteridophyta group have well developed roots, stem and leaves and separate …………….. for conduction of food and water. But,
they do not bear …………….. and ……………… They reproduce with the help of …………….. formed along the back or posterior surface of their leaves. Examples are ferns like Nephrolepis, Marsilea, Pteris, Adiantum, Equisetum, Selaginella, Lycopodium, etc. These plants reproduce …………….. by spore-formation and sexually by …………….. formation. They have a well-developed conducting system.
Answer:
Plants from Pteridophyta group have well developed roots, stem and leaves and separate tissues for conduction of food and water. But, they do not bear flowers and fruits. They reproduce with the help of spores formed along the back or posterior surface of their leaves. Examples are ferns like Nephrolepis, Marsilea, Pteris, Adiantum, Equisetum, Selaginella, Lycopodium, etc. These plants reproduce asexually by spore-formation and sexually by zygote formation. They have a well-developed conducting system.

Question 4.
Phanerogams plants which have special structures for …………….. and produce …………….. In these plants, after the process of reproduction, seeds are formed which contain the …………….. and stored food. During germination of the seed, the stored food is used for the initial growth of the embryo. Depending upon whether seeds are enclosed in …………….. a or not, phanerogams are classified into …………….. and ……………. .
Answer:
Phanerogams plants which have special structures for reproduction and produce seeds. In these plants, after the process of reproduction, seeds are formed which contain the embryo and stored food. During germination of the seed, the stored food is used for the initial growth of the embryo. Depending upon whether seeds are enclosed in a fruit or not, phanerogams are classified into gymnosperms and angiosperms.

Question 5.
Gymnosperms are mostly …………….., perennial and woody. Their stems are without …………….. The leaves form a …………….. These plants bear male and female flowers on different …………….. of the same plant …………….. of these plants do not have natural coverings, i.e. these plants do not form …………….. and are therefore called gymnosperms. (gymnos: naked, sperms: seeds). Examples Cycas, Picea (Christmas tree), Thuja (Morpankhi), Pinus (Deodar), etc.
Answer:
Gymnosperms are mostly evergreen, perennial • and woody. Their stems are without branches. The leaves form a crown. These plants bear male and female flowers on different sporophylls of the same plant. Seeds of these plants do not have natural coverings, i.e. these plants do not form fruits and are therefore called gymnosperms. (gymnos: naked, sperms: seeds). Examples Cycas, Picea (Christmas tree), Thuja (Morpankhi), Pinus (Deodar), etc.

Question 6.
The flowers of Angiosperms plants bear are their …………….. organs Flowers develop into …………….. and seeds are formed within …………….. . Thus, these seeds are ……………..; hence, they are called angiosperms (angios: cover, sperms: seeds). The plants whose seeds can be divided into two equal halves or dicotyledons are called …………….. plants and those whose seeds cannot be divided into equal parts are called …………….. plants.
Answer:
The flowers of Angiosperms plants bear are their reproductive orgAnswer: Flowers develop into fruits and seeds are formed within fruits. Thus, these seeds are covered; hence, they are called angiosperms (angios: cover, sperms: seeds). The plants whose seeds can be divided into two equal halves or dicotyledons are called dicotyledonous plants and those whose seeds cannot be divided into equal parts are called monocotyledonous plants.

Answer the questions in detail:

Question 1.
Write the characteristics of Thallophyta.
Answer:

• Thallophyta plants grow mainly in water.
• The group of plants, which do not have specific parts like root-stem-leaves-flowers but are autotrophic due to the presence of chlorophyll are called algae.
• Algae show great diversity They may be unicellular or multicellular and microscopic or large.
• Some of these are found in freshwater while some are found in saline water.
• Various types of fungi like yeasts and moulds which do not have chlorophyll are also included in this group.
• Examples: Spirogyra, Ulothrix, Ulva, etc.

Question 2.
Write the characteristics of Gymnosperms.
Answer:

• Gymnosperms are mostly evergreen, perennial and woody.
• Their stems are without branches.
• The leaves form a crown.
• These plants bear male and female flowers on different sporophylls of the same plant.
• Seeds of these plants do not have natural coverings, i.e. these plants do not form fruits and are therefore called gymnosperms (gmnos: naked, sperms: seeds)
• Examples: Cycas, Picea (christmas tree), Thuja, Pinus (deodar), etc.

Make concept diagram

Question 1.
Plant classification
Answer:

Question 2.
Taxonomy of carnivorous 1ant
Answer:

Question 3.
Taxonomy of mango plant
Answer:

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 3 Current Electricity Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 3 Current Electricity

Class 9 Science Chapter 3 Current Electricity Textbook Questions and Answers

1. The accompanying figure shows some electrical appliances connected in a circuit in a house. Answer the following questions.

A. By which method are the appliances connected?
Answer:
Appliances are connected in parallel.

B. What must be the potential difference across individual appliances?
Answer:
The potential difference across all appliances is same in parallel connection.

C. Will the current passing through each appliance be the same? Justify your answer.
Answer:
No, as every appliance has a different load (resistance), the current flowing through each appliance will be different.

D. Why are the domestic appliances connected in this way?
Answer:
The domestic appliances are connected in parallel as the potential difference remains same.

E. If the T.V. stops working, will the other appliances also stop working? Explain your answer.
Answer:
No, the other devices will not stop working as the current flowing through them is along different paths.

2. The following figure shows the symbols for components used in the accompanying electrical circuit.

Which law can you prove with the help of the above circuit?
Answer:

(b) This circuit can be used to prove Ohm’s law.
(c) V = 1R is the expression of Ohm’s law

3. Umesh has two bulbs having resistances of 15 W and 30 W. He wants to connect them in a circuit, but if he connects them one at a time the filament gets burnt. Answer the following.

A. Which method should he use to connect the bulbs?
B. What are the characteristics of this way of connecting the bulbs depending on the answer of A above?
C. What will be the effective resistance in the above circuit?

4. The following table shows current in Amperes and potential difference in Volts.

a. Find the average resistance.
b. What will be the nature of the graph between the current and potential difference? (Do not draw a graph.)
c. Which law will the graph prove? Explain the law.

5. Match the pairs

‘A’ Group – ‘B’ Group
1. Free electrons – a. V/ R
2. Current – b. Increases the resistance in the circuit
3. Resistivity – c. Weakly attached
4. Resistances in series – d. VA/LI

6. The resistance of a conductor of length x is r. If its area of crosssection is a, what is its resistivity? What is its unit?

7. Resistances R₁, R₂, R₃ and R₄ are connected as shown in the figure. S₁ and S₂ are two keys. Discuss the current flowing in the circuit in the following cases.

a. Both S₁ and S₂ are closed.
b. Both S₁ and S₂ are open.
c. S₁ is closed but S₂ is open.
Answer:
(a) When both S₁ and S₂ are dosed, the effective resistance of the circuit decreases and hence, current will increase.
(b) When both S₁ and S₂ are open, the effective resistance of the rircuit increases and hence, current will decrease.
(c) When S₂ is closed and S₂ is open, the effective resistance of the tircuit decreases and hence current will increase. [Current will be more than case (b) but less than in case (a)]

8. Three resistances x₁, x₂ and x₃ are connected in a circuit in different ways. x is the effective resistance. The properties observed for these different ways of connecting x₁, x₂ and x₃ are given below. Write the way in which they are connected in each case. (I-current, V-potential difference, x-effective resistance)

a. Current I flows through x₁, x₂ and x₃
b. x is larger than x₁, x₂ and x₃
c. x is smaller than x₁, x₂ and x₃
d. The potential difference across x₁, x₂and x₃ is the same
e. x = x₁ + x₂ + x₃
\(\text { f. } x=\frac{1}{\frac{1}{x_{1}}+\frac{1}{x_{2}}+\frac{1}{x_{3}}}\)

9. Solve the following problems.

A. The resistance of a 1m long nichrome wire is 6Ω. If we reduce the length of the wire to 70 cm. what will its resistance be? (Answer : 4.2Ω)
Answer:
The resistance of 70cm wire will be 4.2 Ω

B. When two resistors are connected in series, their effective resistance is 80Ω. When they are connected in parallel, their effective resistance is 20Ω. What are the values of the two resistances? (Answer : 40Ω, 40Ω)
Answer:
The values of the two resistances R₁ and R₂ are 40Ω and 40Ω.

C. If a charge of 420 C flows through a conducting wire in 5 minutes what is the value of the current? (Answer : 1.4 A)
Answer:
Given: Electric charge (Q) = 420 C
Time (t) = 5 min = 5 x 60
= 300 sec.
To find: Electric current (1) = ?
Formula:
\(I=\frac{Q}{t}\)
Solution:
\(I=\frac{Q}{t}\)
The current in the circuit is 1.4 A.

Class 9 Science Chapter 3 Current Electricity Intext Questions and Answers

Can you recall?

Question 1.
You must have seen a waterfall. Which way does the water flow?
Answer:
Water flows from a certain height of a mountain towards the ground.

Question 2.
Material: Copper and aluminium wires, glass rod, rubber.
Make connection as shown in figure 3.8. First connect a copper wire between points A and B and measure the current in the circuit. Then in place of the copper wire, connect the aluminium wire, glass rod, rubber, etc one at a time and measure the current each time. Compare the values of the current in different cases.

Also take different metal strips (Iron, Copper, Zinc, and Aluminium) and connect it in slot AB. Now observe the difference in the resistance using Ohm meter.
Answer:
When copper and aluminium wires are connected to the circuit, current flows through it, as both are good conductors of electricity. When glass rod or rubber was connected to the circuit, current does not flow through it, as both are bad conductors of electricity.

Copper displays lowest resistance while the resistance increases with aluminium, zinc and iron respectively.

Question 3.
Set up the experiment as shown in figure. Then remove the clamp from the rubber tube.

(a) What happens when the clamp is removed?
Answer:
When the clamp is removed, water flows from higher level to lower level.

(b) Does the water stop flowing? Why?
Answer:
Yes, the water stops flowing. This happens when the level of water becomes equal in both the bottles, i.e., there is no difference in the water levels.

(c) What will you do to keep the water flowing for a longer duration?
Answer:
The difference in the water level has to be maintained till that time. The difference must never be zero.

Question 4.
Point out the mistakes in the figure below:

Answer:
A: Wire is broken at the negative terminal. Bulb will not glow as the circuit is incomplete.
B: Wire is disconnected at the negative terminal. Bulb will not glow as the circuit is incomplete.
C: The circuit is complete. Therefore, bulb will glow.
D: Rubber is a bad conductor of electricity. Hence, it will not allow current to flow and the bulb will not glow.

Question 5.
Why are the bulbs in Figures B, C and D not lighting up?

Answer:

• In B, the blue wire is broken. Hence circuit is incomplete and current does not flow. Therefore, bulb will not light up.
• In C, the red wire is broken. Hence circuit is incomplete and current does not flow. Therefore, bulb will not light up.
• In D, both wires are connected to the same terminal. Hence, there is no potential difference and current does not flow. Therefore, bulb will not light up.

Class 9 Science Chapter 3 Current Electricity Additional Important Questions and Answers

Choose and write the correct option:

Question 1.
1mA = …………… A.
(a) 10³
(b) 10^-3
(c) 10⁶
(d) 10^-6
Answer:
(a) 10³

Question 2.
To increase the effective resistance in a circuit the resistors are connected in ………….. .
(a) Series
(b) Parallel
(c) Both ways
(d) None of these
Answer:
(a) series

Question 3.
1 kilowatt hr = …………… joules.
(a) 4.6 x 10⁶
(b) 3.6 x 10⁶
(c) 30.6 x 10⁶
(d) 3.6 x 1O⁵
Answer:
(b) 3.6 x 10⁶

Question 4.
The voltage difference in India between the live and neutral wires is about ………….. .
(a) 110 V
(b) 220 V
(c) 440 V
(d) 60 V
Answer:
(b) 220 V

Question 5.
Resistivity is the specific property of a ………….. .
(a) Area of cross-section
(b) Temperature
(c) Length
(d) Material
Answer:
(d) material

Question 6.
If a P.D. of 12 V is applied across a 3Ω resistor then the current passing through it is ………….. .
(a) 36 A
(b) 4 A
(c) 0.25 A
(d) 15 A
Answer:
(b) 4 A.

Question 7.
In order to measure the electric current flowing through a circuit, we connect …………… with the circuit.
(a) a voltmeter in parallel
(b) a voltmeter in series
(c) an ammeter in parallel
(d) an ammeter in series
Answer:
(d) an ammeter in series

Question 8.
P and Q are two wires of same length and different cross-sectional areas and made of same material. Name the property which is same for both the wires.
(a) Resistivity
(b) Resistance
(c) Current
(d) Both (a) and (b)
Answer:
(a) Resistivity

Question 9.
The following is true for identical bulbs connected in parallel.
(a) All bulbs glow with unequal brightness.
(b) If one bulb is non-functional, all will stop working.
(c) All bulbs glow with equal brightness.
(d) Bulbs function for longer time.
Answer:
(c) All bulbs glow with equal brightness

Question 10.
The …………… wire is either yellow or green in colour.
(a) Live
(b) Neutral
(c) Earth
(d) Fuse
Answer:
(c) earth

Question 11.
A current flows through a circuit due to the difference in …………… between two points in the conductor.
(a) Gravity
(b) Potential
(c) Resistance
(d) Fuse
Answer:
(b) potential

Question 12.
…………… is the amount of charge flowing through a particular cross sectional area in unit time.
(a) Electric current
(b) Ampere
(c) Volt
(d) Force
Answer:
(a) Electric current

Question 13.
The flow of …………… constitutes the electric current in a wire.
(a) Protons
(b) Neutrons
(c) Electrons
(d) Gravitons
Answer:
(c) electrons

Question 14.
The conventional direction of flow of current is from …………… terminal to …………… terminal.
(a) Negative to positive
(b) Neutral to positive
(c) Positive to negative
(d) Positive to neutral
Answer:
(c) positive, negative

Question 15.
Current stops flowing when potential difference between two ends of a wire becomes ………….. .
(a) Zero
(b) Positive
(c) Negative
(d) Higher
Answer:
(a) zero

Question 16.
Resistances are connected in …………… so as to pass the same current through them.
(a) Series
(b) Parallel
(c) Reversed
(d) Disconnect
Answer:
(a) series

Question 17.
To decrease the effective resistance in a circuit, the resistances are connected in ………….. .
(a) Series
(b) Parallel
(c) Reversed
(d) Disconnect
Answer:
(b) parallel

Question 18.
1μV = …………… V
(a) 10²
(b) 10^-6
(c) 10⁶
(d) 10³
Answer:
(b) 10^-6

Question 19.
Good conductors contain a large number of ………….. .
(a) Protons
(b) Neutrons
(c) Electrons
(d) Gravitons
Answer:
(c) free electrons

Question 20.
Electrons flow from …………… terminal to …………… terminal in a conductor when a potential difference is applied.
(a) Negative to positive
(b) Neutral to positive
(c) Positive to negative
(d) Positive to neutral
Answer:
(a) negative, positive

Find the odd one out:

Question 1.
Voltmeter, Ammeter, Galvanometer, Thermometer
Answer:
Thermometer

Question 2.
Rubber, Silver, Copper, Gold
Answer:
Rubber

Question 3.
Wood, Glass, Steel, Rubber
Answer:
Steel

Question 4.
Graphite, Diamond, Fullerenes, Coal
Answer:
Fullerenes

Distinguish between:

Question 1.
Voltmeter and Ammeter
Answer:

Voltmeter	Ammeter
(i) It is an instrument used to measure the potential difference between two terminals of a cell.	(i) It is an instrument to measure the electric current flowing through a circuit.
(ii) It is connected in parallel with the cell.	(ii) It is connected in series with the cell.
(iii) It has a very high resistance.	(iii) It has a very low resistance.
(iv) Voltmeter has range of volts.	(iv) Ammeter has range of amps.

Question 2.
Ohmic conductors and Non-Ohmic conductors
Answer:

Conductors	Insulators
(i) Substances which have very low electrical resistances are called conductors.	(i) Substances which have extremely high electrical resistances are called Insulators.
(ii) They contain a large number of free electrons.	(ii) They contain practically no free electrons.
(iii) Conductors are mostly metals.	(iii) Insulators are mostly non metals.
(iv) Conductor example iron, copper.	(iv) Insulator example rubber, plastic.

Question 3.
Conductors and Insulators
Answer:

Resistance	Resistivity
(i) The hindrance to the flow of electrons is called resistance.	(i) Resistivity is the specific property of the material of a conductor.
(ii) The S.I. unit of resistance is ohm (Q).	(ii) The S.I. unit of resistivity is ohm-metre (Q – m).
(iii) It depends on temperature, area of cross-section, length of conductor and material of the conductor.	(iii) It depends on material of the conductor.
(iv) Resistance can be changed as it depends of external factor as well.	(iv) Resistivity cannot be changed as it depends of internal factors.

Question 4.
Resistance in Series and Resistance in Parallel
Answer:

Resistance in Series	Resistance in Parallel
(i) Effective resistance of the resistors is equal to the sum of their individual resistances.	(i) Inverse of the effective resistance is equal to the sum of the inverse of individual resistances.
(ii) The same current flows through each resistor.	(ii) The total current flowing through the circuit is the sum of the currents flowing through individual resistors.
(iii) The effective resistance is larger than each of the individual resistances.	(iii) The effective resistance of resistors connected in parallel is less than the least resistance of individual resistors.
(iv) This arrangement is used to increase the resistance in a circuit.	(iv) This arrangement is used to decrease the resistance in a circuit.

Question 5.
Answer:

Electric current	Potential difference
(i) The flow of electric charge per unit time is called electric current.	(i) The difference in potential between the positive and negative terminal of a cell is the potential difference of that cell.
(ii) The S.I. unit of electric current is ampere.	(ii) The S.I. unit of potential difference volt.
(iii) Ammeter is used to measure electric current.	(iii) Voltmeter is used to measure electric current.
(iv) Current is represented by: \(\mathrm{I}=\frac{\mathrm{Q}}{\mathrm{t}}\)	(iv) Potential difference is represented by: \(\mathrm{V}=\frac{\mathrm{W}}{\mathrm{Q}}\)

Make pair:

Question 1.
Copper : Conductor :: Rubber : ……………….
Answer:
Insulator

Question 2.
Aluminium : ………………. :: Indium oxide : Super Insulator
Answer:
Super conductor

Question 3.
Parallel Connection : \(\frac{1}{\mathrm{R}_{p}}=\frac{1}{\mathrm{R}_{1}}+\frac{1}{\mathrm{R}_{2}}\) :: Series Connection : ……………….
Answer:
R_s = R₁ + R₂

(4) Electric Current : ………………. :: Electric charge : Coulomb
Answer:
Ampere

(5) Electric resistance : Ohm :: Potential difference : ……………….
Answer:
Volt

State whether the following statements are true or false. Correct the false statements:

(1) The SI unit of charge is volt.
(2) Voltmeter is always connected in series with the device.
(3) The conventional direction of flow of current is from positive terminal to negative terminal.
(4) Silver and copper are good conductors.
(5) Resistivity of pure metals is more than alloys.
(6) Resistance in series arrangement is used to decrease resistance of circuit.
(7) A conducting wire offers less resistance to flow of electrons.
(8) Charges are measured in ampere.
(9) The unit of potential difference is ampere.
(10) Resistance of a conductor is inversely proportional to the length of the conductor.
(11) Ammeter is connected in parallel to the cell to measure current.
(12) Fuse is made of wire having high melting point.
Answer:
(1) False. The SI unit of charge is coulomb.
(2) False. Voltmeter is ahvays connected in parallel with the device.
(3) True
(4) True
(5) False. Resistivity of pure metals is less than alloys.
(6) False. Resistance in series arrangement is used to increase resistance of circuit.
(7) True
(8) False. Charges are measured in coulomb.
(9) False. The unit of potential difference is volt.
(10) False. Resistance of a conductor is directly proportional to the length of the conductor.
(11) False. Ammeter is connected in series to the cell to measure current.
(12) False. Fuse is made of wire having low melting point.

Answer the following in one sentence:

Question 1.
Which is the unit used to measure large voltages?
Answer:
Kilovolts and Megavolts are the units used to measure large voltages.

Question 2.
What is the SI unit of potential difference?
Answer:
The SI unit of potential difference is volt (V).

Question 3.
What is lightning?
Answer:
Lightning is the electric discharge travelling from clouds at high potential to earth’s surface which is at zero potential.

Question 4.
What is the unit of resistivity.
Answer:
The unit of resistivity is ohm metre (Qm).

Question 5.
Which substances are called conductors of electricity?
Answer:
Those substances which have very low electrical resistance are called conductors of electricity.

Question 6.
What is Earth wire?
Answer:
Earth wire is generally yellow or green colour, it is connected to a metal plate buried deep underground near the house and is for safety purpose.

Write formula:
(1) E1ectriccurrent \(=\frac{Q}{t}\)
(2) Electric charge = It
(3) Potential difference = IR
(4) Electric resistance \(=\frac{V}{I}\)
(5) Current \(=\frac{V}{R}\)
(6) Resistivity \(=\frac{RA}{L}\)

Give scientific reasons:

Question 1.
Free electrons are required for conduction of electricity.
Answer:

• Every atom of a metallic conductor has one or more outermost electrons which are very weakly bound to the nucleus.
• These are called free electrons. These electrons can easily move from one part of a conductor to its other parts. The negative charge of the electrons also gets transferred as a result of this motion.
• The free electrons in a conductor are the carriers of negative charge. Hence, free electrons are required for conduction of electricity.

Question 2.
Wood and glass are good insulators.
Answer:

• Those substances which have infinitely high electrical resistance are called insulators.
• Wood and glass have high resistance and negligible free electrons for conduction of electricity.
• Hence, wood and glass are good insulators.

Question 3.
Connecting wires in a circuit are made of copper and aluminium.
Answer:

• Copper and aluminum are good conductors of electricity.
• They have low electrical resistance and large number of free electrons.
• As they are malleable and ductile, they can be drawn into thin wires. Hence, connecting wires in a circuit are made of copper or aluminum.

Question 4.
A thick wire has a low resistance.
Answer:

• The resistance (R) of a wire is inversely proportional to the cross-sectional area (A) of a wire. i.e., R i
• Thus, greater is the cross-sectional area of a conductor (wire), lower is its resistance. Hence, a thick wire has a low resistance.

Question 5.
A series combination of resistances is used to increase the resistance of a circuit.
Answer:

• When resistances are connected in series, the effective resistance of the resistors is equal to the sum of their individual resistances. R_s = R₁ + R₂ ………….. R_n
• The effective resistance is larger than each of the individual resistances. Hence, This arrangement is used to increase the resistance in a circuit.

Question 6.
A parallel combination of resistances decreases the effective resistance of the circuit.
Answer:

• In a parallel combination, the inverse of the effective resistance is equal to the sum of the inverses of individual resistances. \(\frac{1}{\mathrm{R}_{\mathrm{p}}}=\frac{1}{\mathrm{R}_{1}}+\frac{1}{\mathrm{R}_{2}} \ldots \ldots \cdot \frac{1}{\mathrm{R}_{\mathrm{n}}}\)
• The effective resistance of resistors connected in parallel is less than the individual resistors.
• Due to this, any addition of an individual resistance in parallel combination will decrease the overall resistance of the circuit. Hence, a parallel combination of resistance decreases the effective resistance of the circuit.

Question 7.
Lightning occurs from sky to earth.
Answer:

• Lightning is the electric discharge travelling from clouds at high potential to the earth’s surface, which is at zero potential.
• The earth is always at lower potential as compared to the clouds.
• Hence, lightning occurs from sky to earth.

Question 8.
In streetlights, bulbs are connected in parallel.
Answer:

1. Even if any one of the several bulbs connected in parallel becomes non-functional because of some damage to its filament, the circuit does not break as the current flows through the other paths, and the rest of the bulbs light up.
2. When several bulbs are connected in parallel, they emit the same amount of light as when they are connected individually in the circuit, while bulbs connected in series emit less light than when connected individually. Hence, streetlights are connected in parallel.

Numerical:
Numericals based on the formula: (1) Q= It (2) W= VQ

Question 1.
A current of 0.4 A flows through a conductor for 5 minutes. How much charge would have passed through the conductor?
Answer:
Given: Current (I) = 0.4 A
Time (t) = 5 min = 5 x 60 = 300 s
To find: Charge (Q) =?
Formula: Q = 1 x
Solution: Q = 0.4 x 300
Q= 120 C.
Charge passing through the conductor is 120

Question 2.
Find the amount of work done if 3 C of charge is moved through a potential difference of 9 V.
Answer:

The work done is 27 joule.

Question 3.
The resistance of the filament of a bulb is 1000Ω. It is drawing a current from a source of 230 V. How much current is flowing through it?
Answer:

The current flowing through the filament of bulb is 0.23 A.

Question 4.
The length of a conducting wire is 50 cm and its radius is 0.5 mm. If its resistance is 30Ω, what is the resistivity of its material?
Answer:


The resistivity of the wire is 4.71 x 10^-5 Qm.

Question 5.
A current of 0.24 A flows through a conductor when a potential difference of 24 V is applied between its two ends. What is its resistance?
Answer:

The resistance of a conductor is 100Ω.

Question 6.
If three resistors 15Ω, 3Ω and 4Ω each are connected in series, what is the effective resistance in the circuit?
Answer:
Given:
R₁ =15Ω
R₂ = 3Ω
R₃ = 4Ω
Effective resistance in series (R_s) = ?
R_s = R₁ + R₂ + R₃
R_s = 15 + 3 + 4
R_s = 22Ω
The effective resistance in the circuit is 22Ω.

Question 7.
Three resistances 15Ω, 20Ω and 10Ω are connected in parallel. Find the effective resistance of the circuit.
Answer:


The effective resistance of the circuit is 4.615 Ω. It is less than the least of the three i.e., 10Ω.

Write a note on the following:

Question 1.
Electric current
Answer:
An electric current is the flow of electrons through a conductor. Quantitatively, current
(I) is defined as the charge passing through a conductor in unit time.
\(T=\frac{Q}{t}\)

Question 2.
1 ampere
Answer:
One ampere current is said to flow in a conductor if one coulomb charge flows through it every second.
\(1 \mathrm{~A}=\frac{1 \mathrm{C}}{1 \mathrm{~s}}\)

Question 3.
1 volt
Answer:
The potential difference between two points is said to be 1 volt if 1 joule of work is done in moving 1 coulomb of electric charge from one point to another.
\(1 \mathrm{~V}=\frac{1 \mathrm{~J}}{1 \mathrm{C}}\)

Question 4.
Potential Difference
Answer:
The amount of work done to carry a unit positive charge from point A to point B is called the electric potential difference between the two points.
\(V=\frac{W}{Q}\)

Question 5.
Conductor
Answer:
Those substances which have very low resistance are called conductors. Current can flow easily through such materials.

Question 6.
Insulators
Answer:
Those substances which have extremely high resistance and through which current cannot flow are called insulators.

Question 7.
1 ohm
Answer:
If one Ampere current flows through a conductor when one Volt potential difference is applied between its ends, then the resistance of the conductor is one Ohm.
\(\frac{1 \text { Volt }}{1 \text { Ampere }}=1 \mathrm{Ohm}\)

Question 8.
Potential
Answer:
The level of electric charge present is known as potential.

Question 9.
Ohm’s Law
Answer:
If the physical state of a conductor remains constant, the current (I) flowing through it is directly proportional to the potential difference (V) between its two ends.
V = IR

Question 10.
Superconductors
Answer:
The resistance of some conductors becomes nearly zero if their temperature is decreased up to a certain value close to 0 K. Such conductors are called superconductors.

Question 11.
Non-ohmic conductors
Answer:
Conductors which do not obey Ohm’s law are called non-ohmic conductors.

Complete the flow charts:

(1) Protection from Electricity

(2) Resistance

(3) Resistivity

Write properties/characteristics/advantages of the following:

Superconductors
Answer:
The resistance of these conductors becomes nearly zero if their temperature is decreased up to a certain value close to 0 K. Aluminium is an example of Super Conductor. Superconductors can be used in space missions to increase/ boost the signal strength. They are also used i in the data fibres to increase the speed of data transfer.

Give explanations of the given statements:

Question 1.
Safety precautions are to be taken while using electricity.
Answer:

• Electric switches and sockets should be fitted at a height at which small children cannot reach and put pins or nails inside. Plug wires should not be pulled while removing a plug from its socket.
• Before cleaning an electrical appliance it should be switched off and its plug removed from the socket.
• One’s hands should be dry while handling an electrical appliance, and, as far as possible, one should use footwear with rubber soles.
• As rubber is an insulator, it prevents the current from flowing’ through our body, thereby protecting it.
• If a person gets an electric shock, you should not touch that person. You should switch off the main switch or remove the plug from the socket if possible.
• If not, then you should use a wooden pole to push the person away from the electric wire.

Question 2.
In a domestic circuit colour code is followed while setting up electrical wiring.
Answer:

• The electricity in our homes is brought through the main conducting cable either from the electric pole or from underground cables.
• Usually, there are three wires in the cable.
  (a) Live wire which brings in the current. It has a red or brown insulation.
  (b) Neutral wire through which the current returns. It is blue or black.
  (c) Earth wire is of yellow or green colour. This is connected to a metal plate buried deep underground near the house and is for safety purposes.
• In India, the voltage difference between the live and neutral wires is about 220 V.
• Live and neutral wires are connected to the electric meter through a fuse.
• They are connected through a main switch, to all the conducting wires inside the home so as to provide electricity to every room.
• In each separate circuit, various electrical appliances are connected between the live and neutral wires.
• The different appliances are connected in parallel and the potential difference across every appliance is the same.

Question 3.
Fuse used in electrical circuit can save electrical objects from damage.
Answer:

• Fuse wire is used to protect domestic appliances.
• It is made of a mixture of substances and has a specific melting point.
• It is connected in series to the electric appliances. If for some reason, the current in the circuit increases excessively, the fuse wire gets heated and melts.
• The circuit gets broken and the flow of current stops, thus protecting the appliance.
• This wire is fitted in a groove in a body of porcelain-like non-conducting material. For domestic use, fuse wires with upper limits of 1 A, 2 A, 3 A, 4 A, 5 A and 10 A are used.

Question 4.
Bulbs arranged in parallel glow brighter than bulbs arranged in series.
Answer:

• The amount of light given out by bulbs in parallel combination will be more than that in series combination.
• In parallel combination the resistance of the overall circuit decreases whereas in series it increases, so the current flowing through the bulbs in parallel circuit is more.
• Due to this, intensity of light given out by bulbs in parallel combination is more than the bulbs in series combination.

Complete the following table:
Answer:

Solve the numerical:

Question 1.
The length of a conducting wire is 50 cm and its radius is 0.5 mm. If its resistance is 30Ω, what is the resistivity of its material?
Answer:

The resistivity of the wire is 4.71 x 10^-5 Ωm.

Question 2.
Determine the current that will flow when a potential difference of 33 V is applied between two ends of an appliance having a resistance of 110 Ω. If the same current is to flow through an appliance having a resistance of 500 Ω, how much potential difference should be applied across its two ends?
Answer:

The current is 0.3 A and potential difference to be applied is 150 V.

Question 3.
Determine the resistance of a copper wire having a length of 1 km and diameter of 0.5 mm.
Answer:
Given: Resistivity of copper (p)
= 1.7 x 10^-8 Ω m
Converting all measures into metres.
Length of wire (L) = 1 km
= 1000 m = 10³ m
Diameter of wire (d) = 0.5 mm
= 0.5 x 10^-3m
To find: Resistance of wire (R) = ?
Formula:
\(R=\rho \frac{L}{A}\)
Solution:
If d is the diameter of the wire then, its area of cross-section

The resistance of a copper wire is 85Ω and area of cross section is 0.2 x 10^-6 m²

Question 5.
Two resistors having resistance of 16 and 14 are connected in series. If a potential difference of 18 V Is applied across them, calculate the current flowing through the circuit and the potential difference across each individual resistor.
Answer:


The current in the circuit is 0.6 A and potential across 16 Ω retor is 9.6 volt and 14 Ω resistor is 8.4 voIt.

Question 6.
If the resistors 5 Ω, 10 Ω and 30 Ω are connected in parallel to battery of 12 V, find the effective resistance in the circuit. Calculate the total current and current in each resistor.
Answer:


(a) The total current is 4 A and current in each resistor is 2.4 A, 1.2 A and 0.4 A respectively.
(b) The effective resistance in the circuit is 3Ω.

Complete the diagram and answer the questions:

Question 1.
The following figure shows the symbols for components used in the accompanying electrical circuit.

(a) Place them at proper places and complete the circuit.
(b) Which law can you prove with the help of the above circuit?
(c) State expression for Ohm’s law
Answer:

(b) This circuit can be used to prove Ohm’s law.
(c) V = IR is the expression of Ohm’s law

Question 3.
Explain with the help of a diagram, what are free electrons and how they move through the conductor?

Answer:

• Every atom of a metallic conductor has one or more outermost electrons which are very weakly bound to nucleus.
• These are called free electrons.
• These electrons can easily move from one part of a conductor to its other parts.

Complete the paragraph:

Question 1.
If resistors are connected in series,
Answer:
The same current flows through each resistor. The effective resistance of the resistors is equal to the sum of their individual resistances. The potential difference between the two extremes of the arrangement is equal to the sum of the potential differences across individual resistors. The effective resistance is larger than each of the individual resistances. This arrangement is used to increase the resistance in a circuit. This type of connection is used in electrical heating equipment like geysers, iron, and hair dryers.

Question 2.
If a number of resistors are connected in parallel,
Answer:
The inverse of the effective resistance is equal to the sum of the inverses of individual resistances. The current flowing through an individual resistor is proportional to the r inverse of its resistance and the total current flowing through the circuit is the sum of the currents flowing through individual resistors. The potential difference across all r resistors is the same. The effective resistance of resistors connected in parallel is less than r the least resistance of individual resistors.

This arrangement is used to reduce the resistance in a circuit. Even if any one of the several bulbs connected in parallel becomes non-functional because of some damage to its filament, the circuit does not break as the current flows, through the other paths, and the rest of the bulbs light up. When several bulbs are connected in parallel, they emit the same amount of light as when they are connected individually in the circuit, while bulbs connected in series emit less light than when connected individually.

Read the paragraph and answer the questions.

Electric switches and sockets should be fitted at a height at which small children cannot reach and put pins or nails inside. Plug wires should not be pulled while removing a plug from its socket. Before cleaning an electrical appliance it should be switched off and its plug removed from the socket. One’s hands should be dry while handling an electrical appliance, and, as far as possible, one should use footwear with rubber soles. As rubber is an insulator, it prevents | the current from flowing through our body, thereby protecting it. If a person gets an electric shock, you should not touch that person. You should switch off the main switch and if the switch is too far or you do not know where it is located, then you should remove the plug from the socket if possible. If not, then you should use a wooden pole to push the person away from the electric wire.

(i) Why should the electrical sockets be fitted at a certain height?
Answer:
Electric switches and sockets should be fitted at a height at which small children cannot reach and put pins or nails inside.

(ii) Why plug wires should not be pulled out while removing any electrical device?
Answer:
Plug wires should not be pulled out while removing any electrical device as it may cause the wire to break causing short circuit which can lead to fire or death.

(iii) Why should a person wear footwear with rubber soles while handling electrical appliances. .
Answer:
As rubber is an insulator, it prevents the current from flowing through our body, thereby protecting it. Hence a person should wear footwear with rubber soles while handling electrical appliances.

(iv) Saee is touching an electrical button socket with wet hands what will you advise her and why?
Answer:
We will advise her to dry her hands before touching any electrical sockets or devices as water on the hands can cause an electrical short circuit producing shock to the person touching it.

(v) Sneha is getting an electrical shock what will you do the save her life?
Answer:
We should switch off the main switch and if the switch is too far or we do not know where it is located, then we should remove the plug from the socket if possible. If not, then we should use a wooden pole to push the person away from the electric wire.

(vi) Give a title to the above passage.
Answer:
Precautions to be taken while using electricity

Answer the questions in details:

Question 1.
Find the expression (i.e., derive the expression) for the resistors connected in series.
Answer:
Expression for the resistance connected in series:
(i) Let R₁, R₂ and R₃ be three resistances connected in series between C and D.
(ii) Let R_s be the effective resistance in circuit and V₁, V₂ and V₃ be the potential difference across R₁, R₂ and R₃ respectively.
(iii) Let the potential difference across CD be V.

(iv) In series combination.
v = v₁ + v₂ + v₃ ……………………(i)
By using Ohm’s law
V = IR_s
∴ V₁= IR₁, V₂ = IR₂ and V₃ = 1R₃
Substituting these values in equation (j) we get
IR_s = IR₁ + IR₂ + IR₃
∴ R_s = R₁ + R₂ + R₃
For ‘n’ number of resistors conneded in series we get
R_s = R₁ + R₂ + R₃ + …………………. + R_n

Question 2.
Find the expression (i.e., derive the expression) for the resistors connected in parallel.
Answer:
Expression for the resistance connected in parallel.
(i) Let R₁, R₂ and R₃ be the three resistances connected in parallel combination between points C and D and let R be their effective resistance.
(ii) Let I₁, I₂ and I₃ be the currents flowing through resistances R₁, R₂ and R₃ respectively. Let I be the current flowing through the circuit and V be the potential difference of the cell.

(iii) For parallel combination of resistances,

(iv) Substituting the values of (I, I₁, I₂ and I₃) in equation (i) we get

Question 3.
Find the expression for resistivity of a material.
Answer:
(i) At a given temperature, the resistance (R) of a conductor depends on its length (L), area of cross-section (A) and the material it is made of. If the resistance of a conductor is R, then

(ii) p is the constant of proportionality and is called the resistivity of the material.
(iii) The unit of resistivity in SI units is Ohm metre (Ω m).
(iv) Resistivity is a specific property of a material and different materials have different resistivity. ’

Make the concept diagram and explain:

Question 1.
Make the concept diagram of an electrical circuit and explain the working of a fuse.

Answer:

• Fuse wire is used to protect domestic appliances.
• It is made of a mixture of substances and has a specific melting point.
• It is connected in series to the electric appliances. If for some reason, the current in the circuit increases excessively, the fuse wire gets heated and melts. The circuit gets broken and the flow of current stops, thus protecting the appliance.
• This wire is fitted in a groove in a body of porcelain-like non-conducting material. For domestic use, fuse wires with upper limits of 1A, 2A, 3A, 4A, 5A, and lO Aareused.

(2) Show motion of electrons in an circuit and explain precautions while using an electrical device.
Answer:

• Electric switches and sockets should be fitted at a height at which small children cannot reach and put pins or nails inside. Plug wires should not be pulled while removing a plug from its socket.
• Before cleaning an electrical appliance it should be switched off and its plug removed from the socket.
• One’s hands should be dry while handling an electrical appliance, and, as far as possible, one should use footwear with rubber soles.
• As rubber is an insulator, it prevents the current from flowing through our body, thereby protecting it.
• If a person gets an electric shock, you should not touch that person. You should switch off the main switch or remove the plug from the socket if possible.
• 1f not, then you should use a wooden pole to push the person away from the electric wire.

Q.4.4.Complete the incomplete figure and give an explanation:

Answer:

If the physical state of a conductor remains constant, the current (I) flowing through it is directly proportional to the potential difference (V) between its two ends.

I α V
I = kV (k = constant of proportionality)

This is known as Ohm’s law.
We can obtain the SI unit of resistance from the above formula, Potential difference and current are measured in Volts and Amperes respectively. The unit o resistance is called Ohm. It is indicated by the symbol Ω.

The resistance of one Ohm : If one Ampere current flows through a conductor when one Volt potential difference is applied between its ends, then the resistance of the conductor is one Ohm.

Balbharti Maharashtra State Board Class 9 Political Science Solutions Chapter 5 India and Other Countries Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Political Science Solutions Chapter 5 India and Other Countries

Class 9 Political Science Chapter 5 India and Other Countries Textbook Questions and Answers

1. Choose the right option and rewrite the sentence:

Question 1.
The country that has a free international border with India _______.
(a) Pakistan
(b) Bangladesh
(c) Nepal
(d) Myanmar
Answer:
(c) Nepal

Question 2.
The countries that have tense relations with India _______.
(a) Pakistan and China
(b) Nepal and Bhutan
(c) Myanmar and Maldives
(d) Afghanistan and America
Answer:
(a) Pakistan and China

Question 3.
Factors that have an influence on the relations between India and Pakistan _____.
(a) Difference in the world view of both the countries
(b) Kashmir issue
(c) Nuclear Rivalry
(d) All of the above
Answer:
(d) All of the above

2. Explain with reasons whether the following statements are true or false:

Question 1.
India has an important position among the South Asian countries.
Answer:
True.

• India’s position in Asia is geographically and politically important.
• Afghanistan, Pakistan, Sri Lanka, Bangladesh, Myanmar, Nepal, Bhutan, China and Maldives are India’s neighbours.
• The values of equality and mutual respect have a great importance in India’s foreign policy. India has established relations with neighbouring countries on the basis of these values.
• India is the biggest country in the Indian subcontinent. Similarly, India is economically and technologically more advanced. It is thus natural that India has a great influence among the South Asian countries.

Question 2.
Sino-Indian relations are friendly.
Answer:
False.

• The conflict between India and China is connected to two issues : (a) Border issue and (b) The status of Tibet.
• The border dispute between India and China is related to the Aksai Chin area and the Macmahon line.
• China claims that the area, South of Aksai Chin and Macmahon line (Arunachal Pradesh) is Chinese Territory. China is not willing to agree that Macmahon Line is an international border.
• India made several efforts to sort this border dispute by means of dialogue, but it has not met with much success. In 1962, China Attacked India.
• When China was stepping up its military control in Tibet, Dalai Lama took asylum in India. This issue has been responsible for the conflict between the two countries.

Question 3.
India sent a peacekeeping force to help the Sri Lankan government.
Answer:
True.

• India has friendly relations with the southern neighbour Sri Lanka.
• Political instability in Sri Lanka after 1985 was a result of the differences between the Tamil and the Sri Lankan Government. At that time,
  India had sent a peace keeping force to help the Sri Lankan government.
• Friendly relations with Sri Lanka are important from the point of view of security in the Indian Ocean.

3. Complete the following chart.

Question 1.

Treaties/Exchanges	Countries
…………..	India and Pakistan
Macmahon Line	……………..
…………………	India and Bangladesh
Import of natural gas	…………..
…………..	India and Africa

Answer:

Treaties/Exchanges	Countries
Shimla Agreement, Tashkent Agreement	India and Pakistan
Macmahon Line	India and China
Treaties about sharing river waters and borders	India and Bangladesh
Import of natural gas	Myanmar
Civil Nuclear Agreement	India and Africa

4. Write short notes :

Question 1.
Shimla Agreement
Answer:
(i) India tried to solve Indo-Pak conflict bi-laterally. The Shimla Agreement of 1972 was based on these principles.

(ii) Pakistan considers Kashmir as the biggest hurdle in establishing relations with India.

(iii) The first Indo-Pak war took place in 1965, over Kashmir. The Tashkent Agreement was signed in 1966, but nothing much came out of it.

(iv) Even though the 1971 war was about the creation of Bangladesh, it also had the dimension of the Kashmir problem to it.

(v) The Shimla Agreement in 1972 provided a new format to the interaction between India and Pakistan.

Question 2.
Indo-Nepalese Friendship Treaty
Answer:
(i) The foundation of friendship between India and Nepal was laid with Indo-Nepalese Friendship Treaty in 1950.

(ii) According to this treaty, Nepalese citizens can not only enter India, but they are also permitted to take up government jobs and carry on trade in India.

(iii) The year 1990 marked the beginning of Nepal’s transition to democracy.

(iv) Nepal is dependent upon India for economic progress, basic facilities, food related needs, trade and energy needs.

(v) India sent a lot of help to Nepal at the time of the 2015 earthquake.

Question 3.
MacMahonLine
Answer:
(i) The conflict between India and China is connected to two issues :

• Border issue
• The status of Tibet

(ii) The border dispute between India and China is related to Aksai Chin area and the Macmahon line.
(iii) China claims that the area South of Aksai Chin and Macmahon line (Arunachal Pradesh) is Chinese Territory.
(iv) China is not willing to agree that Macmahon Line is an international border.
(v) India made several efforts to sort this border dispute by means of dialogue, but it has not met with much success.
(vi) In 1962, China attacked India.

Question 4.
Indo-Afghanistan Relation
Answer:
(i) There is a lot of political instability in Afghanistan.

(ii) The dominance of the terrorist organisation, Taliban is responsible for this.

(iii) India has extended help to bring peace, security and stability, curb violence and establish a democratic government.

(iv) Similarly, India is also helping Afghanistan in re-establishing communication facilities that have got destroyed due to war, build roads, cooperate in the fields of science and technology, build schools, health facilities and irrigation projects.

5. Answer the following questions in brief:

Question 1.
Explain the background of cooperative relations between India and America.
Answer:
India and America are two powerful nations who have democratic political systems. Right from the beginning, America was India’s most important trading partner.

(i) Many Indians have gone to America for education or work. Due to the presence of these non-resident Indians, the cultural, social and economic relations between America and India have been increasing.

(ii) After the end of Cold War, the military relations between India and America have increased on a large scale.

(iii) After India accepted free market economy, the speed of economic progress slowly increased. It resulted in further strengthening the trade relations between India and America.

(iv) When India conducted nuclear tests in 1998, there was tension in the relations between the two countries.

(v) Many rounds of discussions took place after that to improve the relations. Through these rounds of talks, America came to believe that India will use its nuclear weapons with responsibility. This completely transformed the Indo-American relations.

(vi) The Civil Nuclear Agreement signed in 2005 that was approved by the U.S. Congress in 2008 was an important landmark in Indo-American relations.

Question 2.
Give some information about the efforts taken by India for the establishment of democracy in neighbouring countries with examples.
Answer:
India upheld sovereignty and democratic values in Nepal, Afghanistan, Sri Lanka and Pakistan.

(i) Nepal was a Hindu Kingdom which adopted democratic government in 2006. India backed up its decision of adopting popular rule by helping Nepal with constitutional guidelines.

(ii) India also extended friendly relations to Ashraf Ghani through SAARC and other international platforms after the collapse of Taliban there.

(iii) India sent a peacekeeping force to Sri Lanka to bring about a cease fire between Sinhalese and Tamils and enforce peace and democracy.

(iv) The regime of Pervez Musharraf had adopted aggressive foreign policies and oppressed public opinion in Pakistan which led to violence and chaos. India had also criticised military rule in Pakistan.

Question 3.
What is the role of South Asian Association for Regional Cooperation?
Answer:
SAARC is a regional organisation established by the South Asian countries in 1985.

(i) The aim of this organisation is to encourage economic co-operation between South Asian nations and thereby achieve the development of the South Asian region.

(ii) The organisation of SAARC is a platform for South Asian countries to come together and discuss common questions and interests.

(iii) Some common interests of South Asian countries are alleviation of poverty, development of agriculture and technological revolution.

(iv) Some treaties were signed on the SAARC platform to make it easy for South Asian countries to trade with each other.

(v) As a part of this, it has been decided that South Asia should be made into a free trade area. For an equitable development of South Asian nations, a treaty about forming South Asian Free Trade Area was signed and South Asian University was established.

6. Give your own opinion about :

Question 1.
What remedies would you suggest in order to reduce the tensions in the relations between India and Pakistan?
Answer:
(i) To reduce tensions in the relations between India and Pakistan, I suggest that

(ii) Cultural exchange between the two nations must be enhanced by allowing and inviting artists of these nations to perform in each other’s countries. Films and sports would also work wonders to improve relations between them.

(iii) Since India is the largest democracy in the world, it should assist and uphold establishment of democratic systems in Pakistan, where government is either overpowered or practically governed by military.

(iv) Pakistan should be convinced through world opinion at international summits, conferences and organisations such as the UN.

(v) India should ascertain that the media does not mislead people in both the nations, by telecasting exaggerated content which might negatively influence the relations.

(vi) India should appeal the Pakistani Government for preservation of Hindu and Sikh pilgrimage places and cultural sites. India must also promote tourism in both the countries, so that civilians across borders have cordial relations.

(vii) Incidents of cross-border terrorism, violence and infiltration must be taken to international forums. Government of India should frame suitable policies for retrieval of Indian subjects, Prisoners of War and fishermen held in captivity of Pakistani Government.

Question 2.
Do you agree with the statement: ‘Hurdles are created in the way of internal development due to tense relations of India with neighbouring countries/ Explain with reasons.
Answer:
(i) Yes, I agree that hurdles are created in the way of internal development due to tense relations of India with neighbouring countries. Due to tense relations with the neighbours, India is unable to focus on the internal law and order situation and social welfare.

(ii) Non-cordial relations with the neighbours will force India to embark on military and nuclear mobilisation to retaliate the pressure of foreign aggression. This might culminate into a war.

(iii) War with neighbours will disturb the peace in the Indian subcontinent and compel India to divert its resources and efforts towards defence and manufacturing weapons.

(iv) Money and resources which should be invested for constructive purposes like health, education and infrastructure would be diverted towards destruction.

(v) A war with her neighbours can put tremendous pressure on India’s economy giving rise to problems like scarcity and inflation.

Question 3.
Do you think that strong healthy relations of India with America are conducive to India’s economic development?
Answer:
(i) Yes, I believe that strong healthy relations of India with America are conducive to India’s economic development.

(ii) America is an undisputable super power of the world and India is on its way to become a super power. Co-operation between these two countries can thwart terrorism in the world, which is a big challenge in the path of economic development.

(iii) Both countries follow democratic systems of government and free market economies. Co-operation from America is a must to enhance India’s economic prospects.

(iv) The non-resident Indians in America have helped to improve on Indian Foreign Reserves. With Indians taking up more employment in America, India can boost its foreign exchange.

(v) Call centres of American MNCs and other ways of outsourcing have provided employment opportunities to the Indian youth. American companies such as Coca Cola, Colgate and MacDonald established their franchises in India, whereas Indian IITians have dominated the Silicon Valley. An Indian – Sundar Pichai, today is the CEO of ‘Google’ – an American company.

(vi) As American companies find Indian economy very promising, FDI has also increased. The ’Make in India’ drive is now seeking empowerment of Indian economy and employment of Indians through such FDI’s.

Class 9 Political Science Chapter 5 India and Other Countries Additional Important Questions and Answers

Choose the correct option from the given options and rewrite the statements:

Question 1.
in l972,______ provided a new format to the interaction between India and Pakistan.
(a) Tashkent Agreement
(b) Shimla Agreement
(c) Civil Nuclear Agreement
(d) Nuclear Non-Proliferation Treaty
Answer:
(b) Shimla Agreement

Question 2.
Aung Sang Su Kyi is credited with having established democracy in ______.
(a) Bhutan
(b) Myanmar
(c) Cambodia
(d) the Maldives
Answer:
(b) Myanmar

Question 3.
The border dispute between India and China is related to ______ area and the Macmahon line.
(a) Sir Creek Area
(b) Siachien
(c) Aksai Chin
(d) Baltistan
Answer:
(c) Aksai Chin

Question 4.
Due to a series of tripartite talks between ____, China and India, Sino-Indian relations are improving slowly.
(a) Pakistan
(b) America
(c) Russia
(d) Japan
Answer:
(b) America

Question 5.
When China was stepping up its military control in Tibet,_____ took asylum in India.
(a) Dalai Lama
(b) Avalokiteshwara
(c) Bodhisattvas
(d) Vajarayana followers
Answer:
(a) Dalai Lama

Question 6.
The ______ signed in 2005 that was approved by the U.S. Congress in 2008 was an important landmark in Indo-American relations.
(a) Comprehensive Test Ban Treaty
(b) Nuclear Non-Proliferation Treaty
(c) Civil Nuclear Agreement
(d) Treaty of Friendship and Co-operation
Answer:
(c) Civil Nuclear Agreement

Question 7.
The policy of increasing trade with South-East Asian nations is known as the ______ policy.
(a) Act East
(b) Pact East
(c) Look East
(d) Seek East
Answer:
(c) Look East

Question 8.
The Summit Conference of India and Africa was held in 2015 with representatives from all _____ African nations attending it.
(a) 54
(b) 56
(c) 58
(d) 53
Answer:
(a) 54

Question 9.
India has co-operated in the project to produced ______ on a large scale, using the water source in Bhutan.
(a) Irrigation facilities
(b) Hydel power
(c) Tube wells
(d) Water reservoirs
Answer:
(b) Hydel power

Question 10.
_______has agreed to extend cooperation and technological help to India in the development and security of coastal areas.
(a) Malaysia
(b) Indonesia
(c) Brunei
(d) Japan
Answer:
(d) Japan

Question 11.
European Nations, especially ______ invest on a large scale in the field of technology in India.
(a) Greece and Italy
(b) Germany and France
(c) Belgium and Netherlands
(d) Spain and Portugal
Answer:
(b) Germany and France

Question 12.
The dominance of the terrorist organisation _______ is responsible for political instability in Afghanistan.
(a) Lashkar-e-Taiba
(b) Jamaat-ud-Dawa
(c) Taliban
(d) Al-Qaeda
Answer:
(c) Taliban

State whether the following statements are true or false with reasons:

Question 1.
Write about India’s relation with Maldives.
Answer:
(i) India’s relations with Maldives have been friendly right from the beginning. This small nation to the South of India is dependent on India for a lot of reasons.

(ii) Trade relations have been established between the two since 1981.

(iii) India has helped Maldives in the development of basic facilities or infrastructure, health and communication.

(iv) From 2006 onwards, co-operation in the military field also started between the two countries.

(v) They have entered into treaties with respect to cooperation in space research, conservation of historical objects and tourism. Similarly, they have decided to co-operate in the area of fighting against terrorism.

Write short notes:

Question 1.
SAARC
Answer:
(i) SAARC is a regional organisation established by the South Asian countries in 1985.

(ii) The aim of this organisation is to encourage economic co-operation between South Asian nations and there by, achieve the development of the South Asian region.

(iii) The organisation of SAARC is a platform for South Asian countries to come together and discuss common questions and interests.

(iv) Some common interests of South Asian countries are alleviation of poverty, development of agriculture and technological revolution.

(v) Some treaties were signed on the SAARC platform to make it easy for South Asian countries to trade with each other.

Do as directed:

Complete the following charts:

Question 1.

S.No	Column ’A’	Column ’B’
(1)	Joint Naval Exercises	……….
(2)	Oil imports	………..
(3)	Security in the Indian Ocean	……….
(4)	Hydel Power Plant	………….

Answer:

S.No	Column ’A’	Column ’B’
(1)	Joint Naval Exercises	Japan
(2)	Oil imports	United Arab Emirates
(3)	Security in the Indian Ocean	Sri Lanka
(4)	Hydel Power Plant	Bhutan

Question 2.

S.No.	Help extended by India	Beneficiary Nations
(1)	Sent Peacekeeping Force to restore peace	Sri Lanka
(2)	Supplies during 2015 earthquake	Nepal
(3)	Communication facilities, roads, science and technology, schools, health and irrigation projects	Afghanistan
(4)	Helped in the freedom struggle	Bangladesh
(5)	Cooperation in the project to produce Hydel Power	Bhutan

Answer:

S.No.	Help extended by India	Beneficiary Nations
(1)	Sent Peacekeeping Force to restore peace	Sri Lanka
(2)	Supplies during 2015 earthquake	Nepal
(3)	Communication facilities, roads, science and technology, schools, health and irrigation projects	Afghanistan
(4)	Helped in the freedom struggle	Bangladesh
(5)	Cooperation in the project to produce Hydel Power	Bhutan

Prepare the following flow charts:

Question 1.

Answer:

Question 2.

Answer:

Question 3.

Answer:

Answer the following questions in brief.

Question 1.
Illustrate the differences in world views between India and Pakistan.
Answer:
(i) India and Pakistan have totally different world views.

(ii) In line with the Indian world view, India opposed the military alliances of the Cold War and tried to solve the Indo-Pak conflict bilaterally.

(iii) On the other hand, Pakistan tried to maintain relations with the Islamic world and China entered into a military agreement with America.

Question 2.
Describe the Kashmir issue between India and Pakistan.
Answer:
(i) Pakistan considers Kashmir as the biggest hurdle in establishing relations with India.

(ii) The first Indo-Pak war took place in 1965 over Kashmir.

(iii) The Tashkent Agreement was signed in 1966, but nothing much came out of it.

(iv) Even though the 1971 war was about the creation of Bangladesh, it also had the dimension of the Kashmir problem to it.

(v) The Shimla Agreement in 1972 provided a new format to the interaction between India and Pakistan.

(vi) In 1999, there was a conflict between India and Pakistan over the infiltration by Pakistan in the Kargil region.

(vii) Even today, the Kashmir question is the basic cause of conflict between the two countries.

Question 3.
Sino-Pak Friendship has affected the security of India. Explain.
Answer:
(i) The threat to India’s security is increasing due to friendship between China and Pakistan, supply of weapons from China to Pakistan and also transfer of missile and nuclear weapons technology.

(ii) The increasing friendship between China and Pakistan and increasing influence of China over India’s other neighbours is a cause of concern for India.

Question 4.
How is India trying to resolve its differences with China?
Answer:
(i) India has always made efforts to improve relations with China.

(ii) A joint executive group has been set up to solve the Sino-Indian border dispute.

(iii) When the rate of economic growth of both India and China increased, the trade relations between both the countries began to get strengthened.

(iv) Because of improvement in economic and trade relations between India and China and a series of tripartite talks between Russia, China and India, Sino-Indian relations are improving slowly.

(v) Even though the border dispute is not completely resolved, it has taken a back seat and relations in other areas have become more important.

Question 5.
How was Bangladesh created?
Answer:
(i) Today’s Bangladesh is the erstwhile East Pakistan. When Pakistan was created, it had two parts: West and East Pakistan.

(ii) There was linguistic difference between them. There were other political conflicts as well.

(iii) The movement to liberate Bangladesh emerged out of this.

(iv) This movement tried to free Bangladesh from the dominance of West Pakistan.

(v) India helped Bangladesh in its freedom struggle. Bangladesh was formed in 1971.

Question 6.
How could India and African nations benefits from each other?
Answer:
(i) Having close relations with Africa will be beneficial from the point of view of both.

(ii) Many countries in Africa are developing rapidly.

(iii) MaharashtraBoardSoLutions.com diness to help in the all-round development of African youth. India has also agreed to give economic help and even grants to bring about development in different areas like technology, agriculture, tourism, etc.

(iv) India’s energy needs can be fulfilled by the energy rich countries like Egypt, Nigeria, Angola and Sudan.

(v) India is making efforts to increase trade with Africa.

Balbharti Maharashtra State Board Class 9 Political Science Solutions Chapter 4 The United Nations Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Political Science Solutions Chapter 4 The United Nations

Class 9 Political Science Chapter 4 The United Nations Textbook Questions and Answers

1. Choose the right option and rewrite the sentence:

Question 1.
This country is not a permanent member of United Nations Security Council _____.
(a) America
(b) Russia
(c) Germany
(d) China
Answer:
(c) Germany

Question 2.
The United Nations has _______ number of members.
(a) 190
(b) 193
(c) 198
(d) 199
Answer:
(b) 193

Question 3.
This international organisation conducts workshops in India on remedial measures to tackle the problem of malnutrition among children
(a) UNICEF
(b) UNESCO
(c) Trusteeship Council
(d) Red Cross
Answer:
(a) UNICEF

2. Explain with reasons whether the following statements are true or false:

Question 1.
The United Nations General Assembly is a platform to discuss global problems.
Answer:
True.

• Every year the General Assembly meets in its session. During the session, the General Assembly discusses important issues like environment, disarmament, etc.
• The significance of the General Assembly lies in it being a platform for representatives of member nations to come together and discuss and make policy decisions on issues of global importance.

Question 2.
The status of all the member nations of the United Nations is not equal.
Answer:
False.

• As mentioned in the principles of UN, all member nations have the same status.
• There is no discrimination among nations based on geographical size, economic or military power.

Question 3.
A resolution can be passed even if China exercises its veto power.
Answer:
False

• China is one of the five permanent members of the UN and the permanent members have veto power.
• If even one of the five permanent members uses it’s veto i.e. gives a negative vote, the decision cannot be taken.

Question 4.
India has played a major role in the work of the United Nations.
Answer:
True.

• India has always sent her troops to participate in the United Nations peacekeeping forces.
• India has participated in bringing issues like decolonisation, disarmament, racial segregation on the United Nations platform.

3. Explain the following concepts:

Question 1.
Veto
Answer:
(i) Security Council has 5 permanent members and 10 non-permanent members.
(ii) For any decision to be taken, the assent of all five permanent members and four non¬permanent members is necessary.
(iii) America, Russia, England, France and China are permanent members of the Security Council. They have the veto power.
(iv) If even one of the five permanent member uses its veto i.e. gives a negative vote, the decision cannot be taken

Question 2.
UNICEF
Answer:
(i) UNICEF is an affiliated organisation of the United Nations.
(ii) It works towards making nutritious food and health care available to children.
(iii) Several workshops were organised in India to find out measures to overcome malnutrition among babies and children.

4. Answer the following questions in brief:

Question 1.
Write the reasons for the establishment of the United Nations.
Answer:
The United Nations is the world’s largest international organisation. The reasons for the establishment of the United Nations are:

(i) Two World Wars were fought at the beginning of the twentieth century.

(ii) Life and property were destroyed on a large scale in these wars.

(iii) As a result, the League of Nations was established after the First World War and the United Nations was established after the Second World War out of a realisation that there has to be a mechanism to establish world peace.

(iv) The League of Nations did not succeed at all.

(v) But after the use of the nuclear weapons in the . Second World War, the idea took root that such destructive wars should be stopped and that it is the collective responsibility of all nations to do so.

(vi) The United Nations was established after the Second World War to instill this understanding among all nations.

(vii) Hence, the United Nations, an international organisation was established to ensure peace and security at the international level.

Question 2.
Write the objectives of the United Nations.
Answer:
The United Nations has its own definite objectives. They are as follows:

• To establish friendly relations among nations.
• To enhance international security by solving international disputes.
• To safeguard and foster human rights and freedom.
• Along with these, the United Nations also aim at enhancing economic cooperation at the international level.

Question 3.
What is the role of the Peacekeeping Forces of the United Nations?
Answer:
(i) The peacekeeping activity of the United Nations involves creating appropriate circumstances favourable for bringing about permanent peace in strife-tom areas.
(ii) The peacekeeping forces help these areas to progress towards peace.
(iii) In conflict ridden areas, security is provided and at the same time, help is extended for establishing peace.
(iv) The United Nations takes up peacekeeping as one of the tasks for safeguarding and fostering peace in the world.

5. Do as directed:

Question 1.
Complete the following chart giving information about the organs of the United Nations.

S.No	Organ	Number of members	Functions
1.	United Nations General Assembly	……….	…………….
2.	United Nations Security Council	…………..	…………….
3.	International Court of Justice	…………..	……………….
4.	Economic and Social Council	…………..	………………..

Answer:

S.No.	Organ	Number of members	Functions
(1)	United Nations General Assembly	193	(1) To elect the non-permanent members of the Security Council. (2)  To choose the United Nations Secretary General and the judges of the International Court of Justice (ICJ) in consultation with the Security Council. (3) To pass the annual budget of the United Nations.
(2)	United Nations Security Council	15 (5 Permanent and 10 NonPermanent)	(1) To maintain international peace and security. (2) To prepare policies for arms control. (3) To play a joint role along with the General Assembly in the appointments of the judges of the International Court of Justice and of the United Nations Secretary General.
(3)	International Court of Justice	15 judges	(1) To settle the disputes between two or more member nations of the United Nations. (2) To interpret international law authentically. (3) To advise the various organs or subsidiary bodies of the United Nations about legal issues.
(4)	Economic and Social Council	54 members	(1) Initiate discussions at the global level on issues like poverty, unemployment, economic and social inequality and suggest policies to tackle these problems. (2) Discuss issues like women’s questions, empowerment of women, human rights, fundamental freedoms, global trade, health related issues, etc., and make decisions. (3) Make efforts to establish cultural and educational cooperation at the international level. (4) Coordinate the functioning of the different organisations working in association with the United Nations.

Question 2.
Show the chronology of the establishment of the United Nations.

Answer:

Question 3.
Complete the following tree diagram about the United Nations.

Answer:

Class 9 Political Science Chapter 4 The United Nations Intext Questions and Answers

Answer the following in brief:

Question 1.
Did India participate in the conferences during the Second World War?
Answer:
India was among the original members of the United Nations that signed the Declaration by United Nations at Washington, D.C. on 1st January, 1942 and also participated in the United Nations Conference on International Organization at San Francisco from 25th April to 26th June 1945.

Question 2.
Which day is celebrated as United Nations day?
Answer:
United Nations was established on 24th October 1945. The day is now celebrated each year . around the world as United Nations Day.

Question 3.
Can the United Nations intervene militarily if there is a serious threat to international peace?
Answer:
The United Nations can’t intervene militarily if there is a serious threat to international peace. The UN, after approval by the Security Council, sends peacekeepers to regions where armed conflict has recently ceased or stalled to enforce the terms of peace agreements and to discourage combatants from resuming hostilities.

Question 4.
What steps have the United Nations taken to foster human rights and freedom?
Answer:
One of the UN’s primary purposes is to promote and encourage respect for human rights and to ensure fundamental freedoms for all without distinction on the basis of race, sex, language, or religion. In 1948, the General Assembly adopted a Universal Declaration of Human Rights. In 1979, the General Assembly adopted the Convention on the Elimination of All Forms of Discrimination against Women, followed by the Convention on the Rights of the Child, in 1989. United Nations Commission on Human Rights was formed in 1993 to oversee human rights issues for the UN.

Question 5.
Only one Indian has so far been the President of the UN General Assembly. Who is that person? When and at which session?
Answer:
Mrs. Vijayalakshmi Pandit is the only Indian so far who has been the President of the UN General Assembly, at the eighth session in 1953.

Activity:

Question 1.
Write the names of United Nations Secretary Generals until now.
Answer:
(i) Mr. Trygve Lie
(ii) Mr. Dag Hammarskjold
(iii) Mr. U. Thant
(iv) Mr. Kurt Waldheim
(v) Mr. Javier Perez de Cuellar
(vi) Mr. Boutros Boutros Ghali
(vii) Mr. Kofi Annan
(viii) Mr. Ban Ki Moon
(ix) Mr. Antonio Guterres

Question 2.
Is it necessary that the Secretary-General should be a citizen of the great powers/the big five?
Answer:
It is not necessary that the Secretary General should be a citizen of one of the great powers/ the big five. Here is the list of Secretary Generals with their countries: Mr. Trygve Lie (Norway) Mr. Dag Hammarskjold (Sweden)

• Mr. U. Thant (Mayanmar)
• Mr. Kurt Waldheim (Austria)
• Mr. Javier Perez de Cuellar (Peru)
• Mr. Boutros Boutros Ghali (Egypt)
• Mr. Kofi Annan (Ghana)
• Mr. Ban Ki Moon (South Korea)
• Mr. Antonio Guterres (Portugal)

Question 3.
Are citizens of a particular country given priority for being Secretary-General?
Answer:
The citizens of no particular country are given priority for being Secretary General.

Question 4.
Who is the current Secretary General and which country does he belong to?
Answer:
The current Secretary General is Antonio Guterres and he belongs to Portugal.

Class 9 Political Science Chapter 4 The United Nations Additional Important Questions and Answers

Choose the correct option from the given options and rewrite the statements:

Question 1.
The United Nations Organisation was founded on _______.
(a) August 9,1944
(b) October 24,1944
(c) October 24,1945
(d) December 10,1945
Answer:
(c) October 24,1945

Question 2.
The United Nations has ____ main organs.
(a) four
(b) five
(c) six
(d) seven
Answer:
(c) six

Question 3.
The United Nations has ______ official languages.
(a) four
(b) five
(c)six
(d) three
Answer:
(c)six

Question 4.
This language is not an official language of the United Nations
(a) French
(b) Spanish
(c) Arabic
(d) Italian
Answer:
(d) Italian

Question 5.
There are ______ permanent members in the Security Council.
(a) four
(b) five
(c)six
(d) seven
Answer:
(b) five

Question 6.
There are ________ non-permanent members in the Security Council.
(a) ten
(b) five
(c) fifteen
(d) seven
Answer:
(a) ten

Question 7.
The term of a non-permanent member of the Security Council is of ______.
(a) four years
(b) five years
(c) two years
(d) one year
Answer:
(c) two years

Question 8.
Which organ of the United Nations has suspended its operations since 1994?
(a) Trusteeship Council
(b) Economic and Social Council
(c) Secretariat
(d) International Court of Justice
Answer:
(a) Trusteeship Council

Question 9.
How many Judges are there in the International Court of Justice?
(a) 9
(b) 10
(c) 12
(d) 15
Answer:
(d) 15

Question 10.
What is the term of the United Nations Secretary General?
(a) 3 years
(b) 4 years
(c) 6 years
(d) 5 years
Answer:
(d) 5 years

Question 11.
UN Secretary General heads which principal organ of the United Nations Organisation?.
(a) General Assembly
(b) Security Council
(c) Economic and Social Council
(d) The Secretariat
Answer:
(d) The Secretariat

Question 12.
What is the term of a judge of the International Court of Justice?
(a) 9 years
(b) 4 years
(c) 6 years
(d) 5 years
Answer:
(a) 9 years

Question 13.
How many members does the Economic and Social Council have?
(a) 33
(b) 40
(c) 15
(d) 54
Answer:
(d) 54

Give the full forms of the following acronyms:

Question 1.
ILO:
Answer:
International Labour Organisation

Question 2.
FAO:
Answer:
Food and Agriculture Organisation

Question 3.
WHO:
Answer:
World Health Organisation

Question 4.
WB:
Answer:
World Bank

Question 5.
IMF:
Answer:
International Monetary Fund

Question 6.
UNICEF:
Answer:
United Nations Children’s Fund

Question 7.
UNESCO:
Answer:
United Nations Educational, Scientific and Cultural Organisation

State whether the following statements are true or false with reasons:

Question 1.
UNICEF is the main organ of UN.
Answer:
False.
(i) The United Nations has six main organs:

1. General Assembly
2. Security Council
3. Economic and Social Council
4. International Court of Justice
5. Trusteeship Council and
6. Secretariat.

(ii) UNICEF is an affiliated organisation of the United Nations. It works towards making nutritious food and health care available to children.

Explain the following concepts:

Question 1.
Millennium Development Goals
Answer:
The United Nations member nations came together in 2000 and decided upon the development goals for the new millennium. Some of the important goals are as follows:

• To eliminate poverty and hunger.
• To make the facilities of primary education available.
• To bring about women’s empowerment, reduce infant mortality rate.
• To take special care of the health of pregnant women.
• To fight diseases like AIDS, malaria, etc.
• To protect the environment and increase the cooperation between developed and developing countries.

Question 2.
International Criminal Court
Answer:
(i) The International Criminal Court is an inter-governmental organisation and an international tribunal.
(ii) Its headquarters are at The Hague in the Netherlands.
(iii) The International Criminal Court has the jurisdiction to prosecute individuals for international crimes of genocide, crimes against humanity and war crimes that are of concern to the international community.

Question 3.
International Court of Justice.
Answer:
(i) International Court of Justice means the judicial branch of the United Nations. The International Court of Justice is located at The Hague in the Netherlands.
(ii) There are 15 judges in the International Court of Justice.
(iii) They are chosen by the General Assembly and the Security Council. Every judge has tenure of nine years.
(iv) Functions:

• To settle the disputes between two or more member nations of the United Nations.
• To interpret international law authentically.
• To advise the various organs or subsidiary bodies of the United Nations about legal issues.

Question 4.
The UN Security Council.
Answer:
Security Council is one of the 6 main organs of the UN:

(i) There are 15 members in the Security Council. Of them, five are permanent members, while ten are non-permanent members.

(ii) The non-permanent members are chosen every two years by the General Assembly. America, Russia, England, France and China are permanent members of the Security Council. They have the veto power.

(iii) For any decision to be taken, the assent of all five permanent members and four non permanent members is necessary. If even one of the five permanent member uses his veto i.e. gives a negative vote, the decision cannot be taken.

(iv) Functions of the Security Council:

(a) The main responsibility of the Security Council is to maintain international peace and security.
The Security Council may suggest one among the following alternatives in situations of international conflict:

• End/resolve conflict and make efforts to establish peace
• Impose economic sanctions or take a decision of military action against the aggressor nation.

(b) To prepare policies for arms control.
(c) To play a joint role along with the General Assembly in the appointments of the judges of the International Court of Justice and of the United Nations Secretary General.

Complete the following table:

Question 1.

(1)	WHO	(a)	………….
(2)	UNESCO	(b)	…………..
(3)	UNICEF	(c)	…………
(4)	ILO	(d)	…………….

Answer:

(1)	WHO	(a)	World Health Organization
(2)	UNESCO	(b)	United Nations Educational Scientific and Cultural Organization
(3)	UNICEF	(c)	United Nations Children’s, Fund
(4)	ILO	(d)	International Labour Organization

Question 2.

(1)	New York	(a)	……….
(2)	Hague, Netherlands	(b)	…………
(3)	San Francisco	(c)	………..

Answer:

(1)	New York	(a)	Headquarters of UN
(2)	Hague, Netherlands	(b)	International Court of Justice
(3)	San Francisco	(c)	Drafting of UN Charter

Complete the flow chart:

Question 1.

Answer:

Complete the chart:

Question 1.

Answer:

Question 2.

Answer:

Answer the following in brief:

Question 1.
State the role of UN General Assembly as platform to discuss global problems.
Answer:
The United Nations General Assembly is a platform to discuss global problems because:

• Every year the General Assembly meets in its session from September to December.
• During the session, the General Assembly discusses important issues like environment, disarmament, etc
• The decisions in the General Assembly are taken by the majority. These decisions are in the form of resolutions.
• The significance of the General Assembly lies in being a platform for representatives of member nations to come together and discuss and make policy decisions on issues of global importance.

Question 2.
United Nations plays an important role in preservation of peace. Explain the statement.
Answer:
(i) The objective of the United Nations is to settle international conflict peacefully.

(ii) The United Nations Charter lays down the ways and means to be employed to achieve this goal.

(iii) It includes appointing an intermediary acceptable to the nations involved in the conflict, use the legal procedure, appoint an arbitrator to solve the dispute and if needed, to take recourse to military means and ensure that conflict will not occur again.

(iv) In modem times, human security has been threatened by terrorism, racist and religious conflict. As a result, the function of securing peace of the United Nations has acquired a lot of importance.

(v) The United Nations makes efforts to ensure that violence does not erupt in strife-tom areas and normalcy is restored as soon as possible, by (for example), starting schools, creating awareness among the people about human rights, making social, economic, political facilities available, conducting elections, etc.

Question 3.
How had India helped to solve international conflicts peacefully?
Answer:
(i) India had participated in the different Conferences that were held before the establishment of the United Nations.

(ii) India has participated in bringing issues like decolonisation, disarmament and racial segregation on the United Nations platform.

(iii) In 1946, India was the first country to raise . the question of racism in the United Nations.India has always led the discussions about the problems of undeveloped and developing countries.

(iv) India has always sent her troops to participate in the United Nations peacekeeping forces. Not just that, India has sent an all-woman peacekeeping force as well.

(v) It is evident from the foregoing analysis that India makes serious efforts to solve international conflicts by peaceful means.

Question 4.
What is the role of UNESCO?
Answer:
UNESCO, is an affiliated organisation of the United Nations works towards peace and security in the world by promoting cooperation between member countries in the fields of education, science and culture.

Question 5.
What are the principles of the United Nations?
Answer:
The United Nations is an organisation created by the coming together of sovereign nations. Naturally, it is based on certain principles or rules. They are as follows:

• All member nations will have the same status. There is no discrimination among nations based on geographical size, economic or military power.
• All member nations of the United Nations should respect the freedom and geographical unity of other member nations.
• All member nations should solve their international disputes and mutual issues peacefully.

Question 6.
What are the functions of the General Assembly?
Answer:
The United Nations General Assembly is a platform to discuss global problems. Functions of General Assembly are:

• To elect the non-permanent members of the Security Council.
• To choose the United Nations Secretary General and the judges of the International Court of Justice (ICJ) in consultation with the Security Council.
• To pass the annual budget of the United Nations.

Question 7.
What are the specialised agencies of UN?
Answer:
(i) Apart from these six major organs, there are many affiliated organisations of the United Nations that help it in its functions. They are called specialised agencies.

(ii) Working in specific areas, they help different nations in those areas.

(iii) The following are some of these important agencies:

• International Labour Organisation (ILO)
• Food and Agriculture Organisation (FAO)
• World Health Organisation (WHO)
• World Bank (WB)
• International Monetary Fund (IMF)
• United Nations Children’s Fund (UNICEF)
• United Nations Educational, Scientific and Cultural Organisation (UNESCO)

Question 8.
Why was the Trusteeship Council setup and why has it suspended its operations?
Answer:
(i) After the Second World War, the territories that were undeveloped were placed under the responsibility of the developed nations.

(ii) The latter were supposed to help bring about the development of the trust territories and once they attain independence from their colonies, help establish democracy.

(iii) The work of the Trusteeship Council is over as there are no trust territories left.

(iv) The work of the Trusteeship Council ended when Palau got independence on 1st November 1994.

Question 9.
Write about the phases in establishment of the United Nations.
Answer:
The United Nations is an international organisation of sovereign nations. It was established in the following manner:

(i) The Atlantic Treaty was signed between Prime Minister of England, Sir Winston Churchill and American, President Franklin D Roosevelt during the Second World War on 14th August 1941.

(ii) According to this treaty, a decision was taken to set up a permanent mechanism to establish international security after the Second World War was over.

(iii) Detailed discussions followed on this decision in two conferences among allied powers in 1944 and 1945.

(iv) A draft of the treaty to establish an international organisation was prepared.

(v) At San Francisco in America, representatives of fifty countries drafted the Charter of the United Nations after discussions.

(vi) As soon as the war was over, the Charter was signed on 24th October, 1945 and the United Nations was established.

Question 10.
Explain the characteristics of the Economic and Social Council.
Answer:
Economic and Social Council:

(i) The main objective of this organisation is to coordinate the economic and social policies of the United Nations.
(ii) The Council has 54 members. They are selected by the General Assembly.
(iii) Each member has a tenure of three years and each year, one-third of the members are newly chosen. Decisions are taken by majority vote.
(iv) Functions:

•  Initiate discussions at the global level on issues like poverty, unemployment, economic and social inequality and suggest policies to tackle these problems.
• Discuss issues like women’s questions, empowerment of women, human rights, fundamental freedoms, global trade, health related issues, etc. and make decisions.
• Make efforts to establish cultural and educational cooperation at the international level.
• Coordinate the functioning of the different organisations working in association with the United Nations.

Activity:

Question 1.
Name the UN Secretary-General who later on became the President of his country.
Answer:
Mr. Kurt Waldheim of Austria.

Question 2.
Name the UN Secretary-General who died in an air-crash.
Answer:
Dag Hammarskjold of Sweden, died on September 18, 1961, during a Congo Mission.

Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 2 Work and Energy Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 9 Science Solutions Chapter 2 Work and Energy

Class 9 Science Chapter 2 Work and Energy Textbook Questions and Answers

1. Write detailed answers?

a. Explain the difference between potential energy and kinetic energy.
Answer:

Kinetic Energy	Potential Energy
(i) Kinetic energy is the energy possessed by the body due to its motion.	(i) Potential energy is the energy possessed by the body because of its shape or position.
(ii) K.E = 1/2 mv2	(ii) P.E = mgh
(iii) e.g., flowing water, such as when falling from a waterfall.	(iii) e.g., water at the top of a waterfall, before the drop.

b. Derive the formula for the kinetic energy of an object of mass m, moving with velocity v.
Answer:
Suppose a stationary object of mass ‘m’ moves because of an applied force. Let ‘u’ be its initial velocity (here u = 0). Let the applied force be ‘F’. This generates an acceleration a in the object, and after time T, the velocity of the object becomes equal to ‘v’. The displacement during this time is s. The work done on the object is
W = F x s ……………….. (1)
Using Newton’s 2nd law of motion,
F = ma ……………….. (2)
Using Newton’s 2nd equation of motion
\(s=u t+\frac{1}{2} a t^{2}\)
However, as initial velocity is zero, u = 0

c. Prove that the kinetic energy of a freely falling object on reaching the ground is nothing but the transformation of its initial potential energy.
Answer:
Let us look at the kinetic and potential energies of an object of mass (m), falling freely from height (h), when the object is at different heights.

As shown in the figure, the point A is at a height (h) from the ground. Let the point B be at a distance V, vertically below A. Let the point C be on the ground directly below A and B. Let us calculate the energies of the object at A, B and C.

(1) Let the velocity of the object be v_B when it reaches point B, having fallen through a distance x.

(2) When the object is stationary at A, its initial velocity is u = 0
∴ K.E = 1/2 mass x velocity2

(3) Let the velocity of the object be vc when it reaches the ground, near point C.

From equations (i) and (iii) we see that the total potential energy of the object at its initial position is the same as the kinetic energy at the ground.

d. Determine the amount of work done when an object is displaced at an angle of 300 with respect to the direction of the applied force.
Answer:
When an object is displaced by displacement ‘s’ and by applying force ‘F’ at an ’angle’ 30°. work done can be given as

e. If an object has 0 momenta, does it have kinetic energy? Explain your answer.
Answer:

• No, it does not have kinetic energy if it does not have momentum.
• Momentum is the product of mass and velocity. If it is zero, it implies that v = 0 (since mass can never be zero).
• Now K.E = ~ mv2, So if v = 0 then K.E also will be zero.
• Thus, if an object has no momentum then it cannot possess kinetic energy.

f. Why is the work done on an object moving with uniform circular motion zero?
Answer:

• In uniform circular motion, the force acting on an object is along the radius of the circle.
• Its displacement is along the tangent to the circle. Thus, they are perpendicular to each other.
  Hence θ = 90° and cos 90 = θ
  ∴ W = Fs cos θ = 0

2. Choose one or more correct alternatives.

a. For work to be performed, energy must be ….
(i) transferred from one place to another
(ii) concentrated
(iii) transformed from one type to another
(iv) destroyed

b. Joule is the unit of …
(i) force
(ii) work
(iii) power
(iv) energy

c. Which of the forces involved in dragging a heavy object on a smooth, horizontal surface, have the same magnitude?
(i) the horizontal applied force
(ii) gravitational force
(iii) reaction force in vertical direction
(iv) force of friction

d. Power is a measure of the …….
(i) the rapidity with which work is done
(ii) amount of energy required to perform the work
(iii) The slowness with which work is performed
(iv) length of time

e. While dragging or lifting an object, negative work is done by
(i) the applied force
(ii) gravitational force
(iii) frictional force
(iv) reaction force

3. Rewrite the following sentences using a proper alternative.

a. The potential energy of your body is least when you are …..
(i) sitting on a chair
(ii) sitting on the ground
(iii) sleeping on the ground
(iv) standing on the ground
Answer:
(iii) sleeping on the ground

b. The total energy of an object falling freely towards the ground …
(i) decreases
(ii) remains unchanged
(iii) increases
(iv) increases in the beginning and then decreases
Answer:
(iii) increases

c. If we increase the velocity of a car moving on a flat surface to four times its original speed, its potential energy ….
(i) will be twice its original energy
(ii) will not change
(iii) will be 4 times its original energy
(iv) will be 16 times its original energy.
Answer:
(ii) will not change

d. The work done on an object does not depend on ….
(i) displacement
(ii) applied force
(iii) initial velocity of the object
(iv) the angle between force and displacement.
Answer:
(iii) initial velocity of the object

4. Study the following activity and answer the questions.

1. Take two aluminium channels of different lengths.
2. Place the lower ends of the channels on the floor and hold their upper ends at the same height.
3. Now take two balls of the same size and weight and release them from the top end of the channels. They will roll down and cover the same distance.

Questions
1. At the moment of releasing the balls, which energy do the balls have?
2. As the balls roll down which energy is converted into which other form of energy?
3. Why do the balls cover the same distance on rolling down?
4. What is the form of the eventual total energy of the balls?
5. Which law related to energy does the above activity demonstrate? Explain.
Answer:
1. At the moment of releasing the ball they possess Potential energy as they are at a height above the ground.
2. As the balls roll down, the Potential energy is converted into Kinetic energy since they are now in motion.
3. Since they have been released from the same height, they will cover the same distance.
4. The eventual form of the total energy of the balls is “Mechanical Energy” i.e, a combination of Potential energy and Kinetic energy
5. The above activity demonstrates the “Law of Conservation of Energy”

5. Solve the following examples.

a. An electric pump has 2 kW power. How much water will the pump lift every minute to a height of 10 m? (Ans : 1224.5 kg)
Answer:
Given:
Power (P) = 2 kW = 2000 W
Height (h) = 10 m
Time (t) = 1 min = 60 s
Acceleration due to gravity (g) = 9.8 m/s²
To Find:
Mass of water (m)= ?
Formula:

Water lifted by the pump is 1224.5 kg

b. If the energy of a ball falling from a height of 10 metres is reduced by 40%, how high will it rebound? (Ans : 6 m)
Answer:
Given: Initial height (h₁) = 10m
Let Initial (P.E₁) = 100
Final (P.E₂) = 100 – 40
= 60

To Find:
Final height (h₂) = ?
Formula:
P.E. = mgh
Solution:

The ball will rebound by 6 m.

d. The velocity of a car increase from 54 km/hr to 72 km/hr. How much is the work done if the mass of the car is 1500 kg? (Ans. : 131250 J)
Answer:


Work done to increase the velocity = 131250 J

e. Ravi applied a force of 10 N and moved a book 30 cm in the direction of the force. How much was the work done by Ravi? (Ans: 3 J)
Answer:
Given:
Force (F) = 10 N
θ = 0°, (Since force and displacement are in same direction)
Displacement (s) = 30 cm = 30/100 m
To Find:
Work (W) = ?
Formula:
W = Fs cos θ
Solution:
W = Fs cos θ
Solution:
The work done by Ravi is 3J

Numericals For Practice

Class 9 Science Chapter 1 Laws of Motion Intext Questions and Answers

Question 1.
What are different types of forces? Give examples.
Answer:
Forces are of two types.

• Contact force e.g.: Mechanical force, frictional force, muscular force
• Non-contact force e.g.: gravitational force, magnetic force, electrostatic force

Question 2.
Monashee wants to displace a wooden block from point A to point B along the surface of a table as shown. She has used force F for the purpose.

(a) Has all the energy she spent been used to produce an acceleration in the block?
(b) Which forces have been overcome using that energy?
Answer:
(a) Only part of the energy applied by Minakshee is used in accelerating the block.
(b) Force of friction has been overcome using the energy.

Question 3.
Mention the type of energy used in the following examples.
(i) Stretched rubber string.
(ii) Fast-moving car.
(iii) The whistling of a cooker due to steam.
(iv) A fan running on electricity.
(v) Drawing out pieces of iron from garbage, using a magnet.
(vi) Breaking of a glass window pane because of a loud noise.
(vii) The drackers exploded in Diwali.
Answer:
(i) Potential energy
(ii) Kinetic energy
(iii) Sound energy
(iv) Electrical energy
(v) Magnetic energy
(vi) Sound energy
(vii) Sound energy, light energy and heat energy

Question 4.
Study the pictures given below and answer the questions:

(a) In which of the pictures above has work been done?
(b) From scientific point of view, when do we say that no work was done?
Answer:
(a) Girl studying : No work done
Boy playing with ball: Work is done
Girl watching T.V.: No work done Person lifting sack of grains : Work is done
(b) No work is said to be done when force is applied but there is no displacement.

Question 5.
Make two pendulums of the same length with the help of thread and two nuts. Tie another thread in the horizontal position.

Tie the two pendulums to the horizontal thread in such a way that they will not hit each other while swinging. Now swing one of the pendulums and observe. What do you see?

Answer:
You will see that as the speed of oscillation of the pendulum slowly decreases, the second pendulum which was initially stationary, begins to swing. Thus, one pendulum transfers its energy to the other.

Question 6.
Ajay and Atul have been asked to determine the potential energy of a ball of mass m kept on a table as shown in the figure. What answers will they get? Will they be different? What do you conclude from this?

Answer:

• According to Ajay P.E₁ = mgh₁ and according to Atul P.E₂ = mgh₂.
• Yes, the answer will be different as the two heights are different.
• Potential energy is relative.

Question 7.
Discuss the directions of force and of displacement in each of the following cases.
(i) Pushing a stalled vehicle.
(ii) Catching the ball which your friend has thrown towards you.
(iii) Tying a stone to one end of a string and swinging it round and round by the other end of the string.
(iv) Walking up and down a staircase; climbing a tree.
(v) Stopping a moving car by applying brakes.
Answer:
(i) Force and displacement are in the same direction.
(ii) Force and displacement are in the opposite direction.
(iii) Force and displacement are perpendicular to each other.
(iv) Force and displacement are in the opposite direction.
(v) Force and displacement are in the opposite direction.

Question 8.
(A) An arrow is released from a stretched bow.
(B) Water kept at a high flows through a pipe into the tap below.
(C) A compressed spring is released.
(a) Which words describe the state of the object in the above examples?
(b) Where did the energy required to cause the motion of the objects come from?
(c) If the obj ects were not brought in those states, would they have moved?
Answer:
(a) Words such as stretched bow, water kept at a height and compressed spring describe the state of the objects.
(b) The energy required for the objects came from its specific state or motion in the form of potential energy.
(c) No, if the objects were not brought in those states, they would have not moved.

Question 9.
Study the activity and answer the following questions.

(a) Figure A – Why does the cup get pulled?
(b) Figure B – What is the relation between the displacement of the cup and the force applied through the ruler?
(c) In Figure C-Why doesn’t the cup get displaced?
(d) What is the type of work done in figures A, B and C?
(e) In the three actions above, what is the relationship between the applied force and the displacement?
Answer:
(a) The cup gets pulled as the force of the nut and the displacement of the cup is in the same direction.
(b) The displacement of the cup and the force applied through the ruler is in the opposite direction.
(c) Tire cup does not get displaced as two equal forces are working in opposite directions.
(d) The work done in figure A is positive, figure B is negative and in figure C is zero.
(e) In figure A the applied force and the displacement is in the same direction, in figure B the applied force and the displacement is in the opposite direction and in figure C the applied force and displacement is perpendicular to each other.

Question 10.
From the following activities find out whether work is positive, negative or zero. Give reasons for your answers.
(a) A boy is swimming in a pond.
(b) A coolie is standing with a load on his head.
(c) Stopping a moving car by applying brakes.
(d) Catching the ball which you friend has thrown towards you.
Answer:
(a) A boy is swimming in a pond: The work done is positive because the direction of applied force and displacement are the same.
(b) A coolie is standing with a load on his head: The work done is zero because the applied force does not cause any displacement.
(c) Stopping a moving car by applying brakes: The work done is negative because the fore applied by the brakes acts in a direction opposite to the direction of motion of car.
(d) Catching the ball which you friend has thrown towards you : Negative work because the force required to stop the ball, acts opposite to the displacement of the ball.

Question 11.
(a) Can your father climb stairs as fast as you can?
(b) Will you fill the overhead water tank with the help of a bucket or an electrical motor?
(c) Suppose Raj ashree, Yash and Ranjeet have to reach the top of a small hill. Raj ashree went by car. Yash went cycling while Ranjeet went walking. If all of them choose the same path, who will reach first and who will reach last? (Think before you answer.
Answer:
(a) No, father takes more time to climb stairs.
(b) Overhead water tank can be filled with the help of one electric motor rather than filling it with bucket.
(c) Raj ashree will reach first, followed by Yash and Ranjeet will reach last because car moves faster than a cycle and a person walking.

Class 9 Science Chapter 1 Laws of Motion Additional Important Questions and Answers

1. Choose and write the correct option:

Question 1.
Forces are of …………………… types.
(a) 2
(b) 3
(c) 4
(d) 5
Answer:
(a) 2

Question 2.
Example of Contact force is ………………….. .
(a) Gravitational Force
(b) Magnetic Force
(c) Electrostatic Force
(d) Muscular Force
Answer:
(d) Muscular Force

Question 3.
Example of Non-contact force is ………………….. .
(a) Mechanical Force
(b) Frictional Force
(c) Muscular Force
(d) Electrostatic Force
Answer:
(d) Electrostatic force

Question 4.
Work is said to be done on a body when a …………………… is applied on object causes displacement of the object.
(a) Direction
(b) Area
(c) Volume
(d) Force
Answer:
(d) force

Question 5.
W = ………………. .
(a) mgh
(b) mdh
(c) mv²
(d) mfe
Answer:
(a) mgh

Question 6.
The energy stored in the dry cell is in of ………………. energy.
(a) Light
(b) Chemical
(c) Solar
(d) Kinetic
Answer:
(b) chemical

Question 7.
The work done is zero if there is no ……………… .
(a) Direction
(b) Displacement
(c) Mass
(d) Angle
Answer:
(b) displacement

Question 8.
Flowing water has ………………. energy.
(a) Potential
(b) Chemical
(c) Solar
(d) Kinetic
Answer:
(d) kinetic

Question 9.
By stretching the rubber strings of a we store ………………. energy in it.
(a) Potential
(b) Chemical
(c) Electric
(d) Kinetic
Answer:
(a) potential

Question 10.
………………. is the unit of force.
(a) Both B and C
(b) Newton
(c) Dyne
(d) Volts
Answer:
(a) Both B and C

Question 11.
For a freely falling body, kinetic energy is ………………. at the ground level.
(a) Maximum
(b) Minimum
(c) Neutral
(d) Reversed
Answer:
(a) Maximum

Question 12.
Energy can neither be ………………. nor ……………… .
(a) Destroyed
(b) Created
(c) Saved
(d) Both A and B
Answer:
(d) Both A and B

Question 13.
Work and …………………… have the same unit.
(a) Energy
(b) Electricity
(c) Force
(d) Both B and C
Answer:
(a) Energy

Question 14.
S.I. unit of energy is ………………….. .
(a) Joule
(b) Ergs
(c) m/s²
(d) Both A and B
Answer:
(a) Joule

Question 15.
Work is the product of ………………….. .
(a) force and distance
(b) displacement and velocity
(c) kinetic and potential energy
(d) force and displacement
Answer:
(d) force and displacement

Question 16.
S.I. unit of work is ………………….. .
(a) dyne
(b) newton-meter or erg
(c) N/m2 or joule
(d) newton-meter or joule
Answer:
(d) newton-meter or joule

Question 17.
…………………… is the capacity to do work.
(a) Energy
(b) Force
(c) Power
(d) Momentum
Answer:
(a) Energy

Question 18.
Kinetic energy of a body (KE) = ………………….. .
(a) mv²
(b) ¹/₂ mv²
(c) mgh
(d) Fs
Answer:
(b) ¹/₂ mv²

Question 19.
Potential energy of a body is given by (P.E.) = ………………….. .
(a) Fs
(b) mgh
(c) ma
(d) mv²
Answer:
(b) mgh

Question 20.
1 hp = ………………….. .
(a) 476 watts
(b) 746 watts
(c) 674 watts
(d) 764 watts
Answer:
(b) 746 watts

Question 21.
…………………… is the commercial unit of power.
(a) kilowatt second
(b) dyne
(c) kilowatt
(d) erg
Answer:
(c) kilowatt

Question 22.
1 kWh = …………………… joules.
(a) 3.6 x 10³
(b) 3.6 x 10⁶
(c) 6.3 x 10⁶
(d) 6.3 x 10³
Answer:
(b) 3.6 x 10⁶

Based on Practicals

Question 23.
The work done by a force is said to be …………………… when the applied force does not produce displacement.
(a) positive
(b) negative
(c) zero
(d) none of these
Answer:
(c) zero

Question 24.
When some unstable atoms break up, they release a tremendous amount of …………………… energy.
(a) chemical
(b) potential
(c) nuclear
(d) mechanical
Answer:
(c) nuclear.

Name the following:

Question 1.
Unit of energy used for commercial purpose.
Answer:
Kilowatt-hour kW h is the unit of energy used for commercial purpose.

Question 2.
Unit used in industry to measure power.
Answer:
Horse power (hp) is the unit used in industry to express power.

Question 3.
SI unit of energy.
Answer:
SI unit of energy is Joule (J).

Question 4.
Two types of mechanical energy.
Answer:
Potential energy and kinetic energy are the two types of mechanical energy.

Question 5.
An example where force acting on an object does not do any work.
Answer:
In a simple pendulum, the gravitational force acting on the bob does not do any work as there is no displacement in the direction of force.

Question 6.
The relationship between 1 joule and 1 erg.
Answer:
1 joule = 107 erg.

Question 7.
Various forms of energy
Answer:
The various forms of energy are mechanical, heat, light, sound, electro-magnetic, chemical, nuclear and solar.

State whether the following statements are true or false:

(1) The potential energy of a body of mass 1 kg kept at height 1 m is 1 J.
(2) Water stored at some height has potential energy.
(3) Unit of power is joule.
(4) Mechanical energy can be converted into electrical energy.
(5) Work is a vector quantity.
(6) Power is a scalar quantity.
(7) The kilowatt hour is the unit of energy.
(8) The CGS unit of energy is dyne.
(9) The SI unit of work is newton.
(10) Kinetic energy has formula – mv²
Answer:
(1) False
(2) True
(3) False
(4) True
(5) False
(6) True
(7) True
(8) False
(9) False
(10) True

Find the odd man out.

Question 1.
Work, Energy, Power, Force.
Answer:
Force.

Question 2.
A stretched spring, A body placed in at some height, A bullet fired from gun.
Answer:
A bullet fired from gun.

Question 3.
A stretched spring, A rock rolling downhill, A bullet fired from gun.
Answer:
A stretched spring.

Write the formula of the following.

Question 1.
Kinetic energy
Answer:
\(\frac{1}{2}\)mv²

Question 2.
Potential energy
Answer:
mgh

Question 3.
Work
Answer:
Fs or Fs cosθ

Question 4.
Force
Answer:
ma

Question 5.
Power
Answer:
\(\frac{w}{1}\)

One line answer.

Question 1.
(i) When is work done said to be zero?
Answer:
Work done is zero when force acting on the body and its displacement are perpendicular to each other.

(ii) Which quantities are measured in ergs?
Answer:
Work and energy are measured in ergs.

(iii) What is the relationship between newton, meter and joule?
Answer:
1 joule = 1 newton x 1 meter

(iv) What is energy?
Answer:
The ability of a body to do work is called energy.

(v) Give 4 examples of energy
Answer:
Solar, wind, mechanical and heat.

(vi) Which device converts electrical energy into heat?
Answer:
Electric water heater (Geyser) converts electrical energy into heat.

(vii) What is the relationship between second, horsepower and joule?
Answer:
1 horse power = \(\frac{746 \text { joules }}{1 \text { second }\)

Question 2.
Find whether work is positive, negative or zero.

(a) Person moving along circle from A to B.
Answer:
Work done is positive as direction of applied force and displacement are the same.

(b) Person completing one circle and returns to position A.
Answer:
Work done is zero because there is no displacement for the person.

(c) Person pushing a car in the forward direction.
Ans,
Work done is positive as the motion of car is in the direction of the applied force.

(d) A car coming downhill even after pushing it in the opposite uphill direction.
Ans,
Work done is negative as the motion of car is in opposite direction of the applied force.

(e) Motion of the clock pendulum.
Answer:
work done is zero as there is no displacement of the pendulum and it comes back to its original position.

Give Scientific reasons:

Question 1.
A moving ball hits a stationary ball and displaces it.
Answer:

• The moving ball has certain energy.
• When it hits the stationary ball, the energy is transferred to the stationary ball, because of which it moves.
• Hence, a moving ball hits a stationary ball and displaces it.

Question 2.
Flowing water from some height can rotate turbine.
Answer:

• Flowing water has certain energy.
• When it hits the turbine, energy is transferred to the turbine, because of which it rotates.
• Hence, flowing water from some height can rotate a turbine.

Question 3.
A stretched rubber band when released regains its original length.
Answer:

• When we stretch a rubber band we give energy to it.
• This energy is stored in it.
• Hence, when we release it, it regains its original length.

Question 4.
Wind can move the blades of a windmill.
Answer:

• Wind has certain energy.
• When it hits the windmill energy is transferred to the windmill because of which it moves.
• Hence, wind can move the blades of a wind mill.

Question 5.
An exploding firecracker lights up as well as makes a sound.
Answer:

• The exploding firecracker converts the chemical energy stored in it into light and sound respectively.
• Here, energy is converted from one type to another.
• Hence, an exploding firecracker lights as well as makes a sound.

Question 6.
Work done on an artificial satellite by gravity is zero while moving around the earth.
Answer:

• When the artificial satellite moves around the earth in a circular orbit, gravitation force acts on it.
• The gravitational force acting on the satellite and its displacement are perpendicular to each other. i.e. 0 = 90°
• For 0 = 90°, work done is zero. [ v cos 90 = 0)
• Hence, work done on an artificial satellite by gravity is zero while moving around the earth.

Difference between :

Question 1.
Work and Power:
Answer:

Work	Power
(i) Work is the product of force and displacement. (ii) Work is given by the formula : W = Fs (iii) MKS unit – joule, CGS unit-erg	(i) Power is the rate of doing work. (ii) Power is given by the formula : \(\mathrm{P}=\frac{\mathrm{W}}{\mathrm{t}}\) (iii) MKS unit – joule/sec, CGS unit – erg/sec

Question 2.
Work and Energy:
Answer:

Work	Energy
(i) It is the product of the magnitude of the force acting on the body and the displacement of the body in the direction of the force. (ii) It is the effect of energy.	(i) It is the capacity to do work. (ii) It is the cause of work.

Solve the following:

Type – A

Formula:
W = Fs cosθ
If force and displacement are in same direction, then θ = 0°, and cos θ = 1
If force and displacement are in opposite direction, then θ = 180°, and cos θ = -1
If force and displacement are perpendiculars, then θ = 90°, and cos θ = 0

Question 1.
Pravin has applied a force of 100 N on an object, at an angle of 60° to the horizontal. The object gets displaced in the horizontal direction and 400 J work is done. What is the displacement of the object? (cos 600 =12)
To Find:
Displacement (s) = ?
Formula:
W = Fs cos θ
Solution:

The object will be displaced through 8 m.

Question 2.
A force of 50 N acts on an object and displaces it by 2 m. If the force acts at an angle of 60° to the direction of its displacement, find the work done.
Answer:
50 J

Question 3.
Raj applied a force of 20 N and moved a book 40 cm in the direction of the force. How much was the work done by Raj?
Answer:
8J

Type -B

Formula:
1) W = K.E = 1/2 mv2
2) W = P.E = mgh
• W = P.E, W = K.E
1 km/hr =
\(\frac{1000}{3600} \mathrm{~m} / \mathrm{s}=\frac{5}{18} \mathrm{~m} / \mathrm{s}\)

Question 4.
A stone having a mass of 250 gm is falling from a height. How much kinetic energy does it have at the moment when its velocity is 2 m/s?
Answer:


The kinetic energy of the stone is 0.5 J

Question 5.
500 kg water is stored in the overhead tank of a 10 m high building. Calculate the amount of potential energy stored in the water.
Answer:
Given:
Mass (m) = 500 kg
Height (h) = 10 m
Acceleration due to gravity (g) = 9.8 m/s²
To Find:
Potential energy (P.E) = ?
Formula:
P.E = mgh
Solution:
P.E = mgh
= 500 x 9.8 x 10
= 500 x 98
= 49000J
The P.E of the stored water is 49000 J

Question 6.
Calculate the work done to take an object of mass 20 kg to a height of 10 m. (g = 9.8 m/s²)
Answer:
Given:
Mass (m) = 20 kg
Acceleration due to gravity (g) = -9.8 m/s²
Displacement (s) = (h) = 10 m.
To Find:
Work done (W) = ?
Formula:
(i) W = P.E = mgh
Solution:
W = mgh
= 20 x (-9.8) x 10
= -1960J
The work done to take an object of mass 20 kg to a height of 10 m is -1960 J.

Question 7.
A body of 0.5 kg thrown upwards reaches a maximum height of 5 m. Calculate the work done by the force of gravity during this vertical displacement.
Answer:
Given:
Mass (m) = 0.5 kg
Acceleration due to gravity (g) = -9.8 m/s²
Displacement (s) = 5 m.
To Find:
Work done (W) = ?
Formula:
W = P.E = mgh
Solution:
W = mgh
= 0.5 x (-9.8) x 5
= -24.5 J
The work done by the force of gravity is -24.5 joule.

Question 8.
1 kg mass has a kinetic energy of 2 joule. Calculate its velocity.
Answer:
Given:
Mass (m) = 1 kg
Kinetic Energy (K.E) = 2 J
To Find:
Velocity (v) = ?
Formula:

The velocity is 2 m/s

Question 9.
A rocket of mass 100 tonnes is propelled with a vertical velocity 1 km/s. Calculate kinetic energy.
Answer:

The kinetic energy of the rocket is 5 x 10¹⁰ J

Type – C

Formula:
\(\text { 1) Power }=\frac{\text { work }}{\text { time }}=\frac{\text { mgh }}{t}\)

Power should be expressed in kW
Time should be expressed in hours
1 k Wh = 1 unit

Question 10.
Swaralee takes 20 s to carry a bag weighing 20 kg to a height of 5 m. How much power has she used?
Given:
Mass (m) = 20 kg
Height (h) = 5 m
Time (t) = 20s
Acceleration due to gravity (g) = 9.8 m/s²
To Find:
Power (P) = ?
Formula:
\(\mathrm{P}=\frac{\mathrm{mgh}}{\mathrm{t}}\)
Solution:
\(\begin{aligned}
P &=\frac{m g h}{t} \\
&=20 \times 9.8 \times \frac{5}{20} \\
&=9.8 \times 5
\end{aligned}\)
= 49 W
Power used by Swaralee is 49 W

Write notes on the following:

Question 1.
Derive the expression for potential energy.
Answer:
(i) To carry an object of mass ‘m’ to a height ‘h’ above the earth’s surface, a force equal to ‘mg’ has to be used against the direction of the gravitational force.

(ii) The amount of work done can be calculated as follows:
Work = force x displacement
∴ W = mg x h
∴ W = mgh

(iii) The amount of potential energy stored in the object because of its displacement.
PE = mgh (W = P.E)

(iv) Displacement to height h causes energy equal to mgh to be stored in the object.

Question 2.
When can you say that the work done is either positive, negative or zero?
Answer:

• When the force and the displacement are in the same direction, the work done by the force is positive.
• When the force and displacement are in the opposite directions, the work done by the force is negative.
• When the applied force does not cause any displacement or when the force and the displacement are perpendicular to each other, the work done by the force is zero.

Question 3.
Explain the relation between, the commercial and SI unit of energy.
Answer:
The commercial unit of energy is a kilowatt-hour (kWh) while the SI unit of energy is the joule. Their relation is
1 kWh = 1kW x 1hr
= 1000 Wx 3600 s
= 3600000J
(Watt x Sec = Joule)
1 kWh = 3.6 x 106 J.

Question 4.
How is work calculated if the direction of force and the displacement are inclined to each other?
Answer:
If the direction of force and the displacement are inclined to each other then, we must convert the applied force into the force acting along the direction of displacement.

If θ is angle between force and displacement, then force (F₁) in direction of displacement is

Complete the flow chart.

Question 1.
Transformation of energy

Answer:

Question 2.
Transformation of energy

Answer:

Write effects of the following with examples.

Question 1.
Force
Answer:

• A force can move a stationary object. The force of engine makes a stationery car to move.
• A force can stop a moving object. The force of brakes can stop a moving car.
• A force can change the speed of a moving object. When a hockey player hits a moving ball, the speed of ball increases.
• A force can change the direction of a moving object. In the game of carrom ,when we take a rebound then the direction of striker changes because the edge of the carrom board exerts a force on the strike.
• A force can change the shape and size of an object. The shape of kneaded wet clay changes when a potter converts it into pots of different shapes and sizes because the p otter applies force on the kneaded wet clay.

Give two examples in each of the following cases:

Question 1.
Potential energy
Answer:

• Water stored in a dam
• A compressed spring

Question 2.
Kinetic energy
Answer:

• Water flowing
• Bullet fired from a gun

Question 3.
Chemical energy
Answer:

• Chemical in cell
• Explosive mixture of a bomb

Question 4.
Zero work done
Answer:

• A stone tied to a string and whirled in a circular path
• Motion of the earth and other planets moving around the sun

Question 5.
Negative work done
Answer:

• A cyclist applies brakes to his bicycle, but the bicycle still covers some distance.
• When a body is made to slide on a rough surface, the work done by the frictional force.

Question 6.
Positive work done
Answer:
(i) A boy moving from the ground floor to the first floor.
(ii) A fruit falling down from the tree.
= 0.5 hr x 30 days
= 15 hrs
To Find:
Energy consumed = ?

The units of energy consumed in the month of April by the iron is 18 units.

Question 7.
A 25 W electric bulb is used for 10 hours every day. How much electricity does it consume each day?
Answer:
Given:
Power (P) = 25 W
25/1000 kW
Time (E) = 10 hrs
To Find:
Electric energy consumed = ?
Formula:
Electric energy consumed = power x time
Solutions:
Electric energy consumed = power x time
= 25/1000 x 10
= 0.25 kWh
The electric bulb consumes 0.25 kWh of electricity each day.

Question 8.
If a TV of rating 100W is operated for 6 hrs per day, find the amount of energy consumed in any leap year?
Answer:

= 2196 hrs.
To Find:
Electric energy consumed
Formula:
Electric energy consumed = power x time
Solution:
Electric energy consumed = power x time
= 0.1 x 2196
= 219.6 kWh
The amount of energy consumed is 219.6 kWh

Complete the paragraph.

Question 1.
………….. is the measure of energy transfer when a force (F) moves an object through a ………….. (d). So when ………….. is done, energy has been transferred from one energy store to another, and so: energy transferred = ………….. done. Energy transferred and work done are both measured in ………….. (J)
Answer:
Work is the measure of energy transfer when a force (F) moves an object through a distance (d). So when work is done, energy has been transferred from one energy store to another, and so: energy transferred = work done. Energy transferred and work done are both measured in joules (J).

Question 2.
………….. energy and ………….. done are the same thing as much as ………….. energy and work done are the same thing. Potential energy is a state of the system, a way of ………….. energy as of virtue of its configuration or motion, while ………….. done in most cases is a way of channeling this energy from one body to another.
Answer:
Potential energy and work done are the same thing as much as kinetic energy and work done are the same thing. Potential energy is a state of the system, a way of storing energy as of virtue of its configuration or motion, while work done in most cases is a way of channeling this energy from one body to another.

Question 3.
In physics, ………….. is the rate of doing work or, i.e., the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the ………….. equal to one ………….. per second.

Power is a ………….. quantity that requires both a change in the physical system and a specified time interval in which the change occurs. But more ………….. is needed when the work is done in a shorter amount of time.
Answer:
In physics, power is the rate of doing work or, i.e., the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt. equal to one joule per second.

Power is a scalar quantity that requires both a change in the physical system and a specified time interval in which the change occurs. But more power is needed when the work is done in a shorter amount of time.

Activity-based questions

Answer in detail:

Question 1.
State the expression for work done when displacement and force makes an angle θ OR State the expression for work done when force is applied making an angle θ with the horizontal force.

Answer:
Let ‘F’ be the applied force and Fj be its component in the direction of displacement. Let ’S’ be the displacement.

The amount of work done is given by W = F₁s ……………………………………… (1)
The force ‘F’ is applied in the direction of the string.

Let ‘θ’ be the angle that the string makes with the horizontal. We can determine the component ‘F₁‘, of this force F, which acts in the horizontal direction by means of trigonometry.
\(\begin{aligned}
\cos \theta=\frac{\text { base }}{\text { hypotenuse }} \\
\therefore \quad \cos \theta=\frac{\mathrm{F}_{1}}{\mathrm{~F}} \\
\therefore \quad \mathrm{F}_{1}=\mathrm{F} & \cos \theta
\end{aligned}\)
Substituting the value of F₁ in equation 1
Thus, the work done by F₁ is
W cos θ s
∴ W = Fscosθ

Question 2.
When a body is dropped on the ground from some height its P.E is converted into K.E but when it strikes the ground and it stops, what happens to the K.E?
Answer:
When a body is dropped on the ground, its K.E appears in the form of:

• Heat (collision between the body and the ground).
• Sound (collision of the body with the ground).
• The potential energy of change in state of the body and the ground.
• Kinetic energy is also utilized to do work i.e., the ball bounces to a certain height and moves to a certain distance vertically and horizontally till Kinetic energy becomes zero.
• The process in which the kinetic energy of a freely falling body is lost in an unproductive chain of energy is called the dissipation of energy.

Question 3.
Explain the statement “Potential Energy is relative”.
Answer:

• The potential energy of an object is determined and calculated according to a height of the object with respect to the observer.
• So, the person staying on 6th floor more potential energy than those staying on the 3rd floor.
• But, the person on the 6th floor will have lesser potential energy than on the 8th floor. Hence potential energy is relative.