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Balbharti Maharashtra State Board Class 7 Civics Solutions Chapter 1 Introduction to Our Constitution Notes, Textbook Exercise Important Questions and Answers.

Maharashtra Board Class 7 Civics Solutions Chapter 1 Introduction to Our Constitution

Class 7 Civics Chapter 1 Introduction to Our Constitution Textbook Questions and Answers

1. Explain the following concepts:

Question 1.
Provisions in the Constitution
Answer:
It is the basic or fundamental law that is stated directly in the Constitution. Therefore, the rules and provisions in the Constitution are the basic or fundamental law of the land. The government is bound to carry out the administration of the country as per the provisions of the Constitution.

Question 2.
Constitution Day
Answer:
The Constituent Assembly enacted the Constitution and adopted it on 26th November, 1949. Therefore, 26th November is observed as ‘Constitution Day’ in India.

2. Discuss:

Question 1.
A Constituent Assembly was established.
Answer:
(i) The process of the making of the Indian Constitution started in 1946.

(ii) The leaders of the freedom movement insisted that independent India will be governed not by the laws made by the British, but by laws made by Indians themselves.

(iii) A Committee was established to prepare the Constitution of Independent India and it came to be known as Constituent Assembly.

Question 2.
Dr. Babasaheb Ambedkar is called the ‘Architect of the Indian Constitution’.
Answer:
(i) The draft of the Constitution was prepared by Dr. Babasaheb Ambedkar and presented to the Constituent Assembly after an in-depth contemplation and study of the Constitution of different countries of the world.

(ii) It was discussed Article by Article. Many amendments were suggested by different members.

(iii) Dr. Babasaheb Ambedkar would present the draft, answer the various questions raised on them and make changes in the draft as per the suggestions of the Constituent Assembly in order to make every provision of the Constitution flawless.

(iv) Due to his contribution towards the making of the Constitution, Dr. Babasaheb Ambedkar is called the ‘Architect of the Indian Constitution’.

Question 3.
What is included in the administration of a country?
Answer:
(i) The Government has to make laws relating to several subjects such as defending the boundaries, protecting the people from external aggression, eradication of poverty, creating employment, education and health services, encouragement to commerce and industries, protection of the weaker sections, making policies for the progress of women, children and the tribal people, etc.

(ii) In short, governments in modem times have to take decisions related to different issues right from space research to public cleanliness. This is included in the administration of a country

3. Choose the right option:

Question 1.
The Constitution of this country is primarily unwritten
(a) America
(b) India
(c) England
(d) None of these
Answer:
England

Question 2.
Who was the President of the Constituent Assembly
(a) Dr. Babasaheb Ambedkar
(b) Dr. Rajendra Prasad
(c) Durgabai Deshmukh
(d) B.B. Rai
Answer:
Dr. Rajendra Prasad

Question 3.
Who among these was not a member of the Constituent Assembly?
(a) Mahatma Gandhi
(b) Moulana Azad I
(c) RajkumariAmritKaur
(d) Hansaben Mehta I
Answer:
Mahatma Gandhi

Question 4.
Who was the Chairman of the Drafting Committee
(a) Dr. Rajendra Prasad
(b) Sardar Vallabhbhai Patel
(c) Dr. Babasaheb Ambedkar
(d) J.B. Kripalani
Answer:
Dr. Babasaheb Ambedkar

4. Answer the following questions:

Question 1.
On what subjects does the Government have to make laws?
Answer:
Government has to make laws relating to several subjects:

• Defending the boundaries.
• Protecting the people from external aggression.
• Eradication of poverty.
• Creating employment, education and health services, encouragement to commerce and industries.
• Protection of the weaker section, making policies for the progress of women, children and the tribal people.

Question 2.
Why do we celebrate 26th January as Republic Day?
Answer:

• Our country began to be governed according to the provisions of the Constitution from 26th January, 1950.
• The Indian Republic came into existence from this day.
• Therefore, 26th January is celebrated as Republic Day.

Question 3.
What are the advantages of running the government as per the provisions of the Constitution?
Answer:
There are several advantages of governing a country with the help of rules or provisions included in a Constitution:

(i) The Government has to function within a set of rules. This reduces the possibility of the misuse of the power and authority they have been given.

(ii) A Constitution includes the rights and freedom of the citizens. The Government cannot take away these rights. Therefore, people’s rights and freedoms are safeguarded.

(iii) Running a country as per the provisions of the Constitution is the same as establishing the rule of law, so there is no scope for the misuse of power or high-handed administration.

(iv) If a country is run as per the Constitution, the faith that the common people have in the government increases. They then become more keen on participating in the activities of the government. Democracy is strengthened due to the increased participation of the people.

(v) The Constitution presents some political ideals before the country. The nation is also bound to act in that direction. It creates an atmosphere conducive to attain world peace and security, and preservation of human rights.

(vi) Since the Constitution also includes the list of citizens’ duties, it fixes the responsibility of the citizens as well.

Activities

1. Several committees were established for the effective functioning of the Constituent Assembly. Find out more information about them and discuss the role of different committees.
2. Prepare a report on how you celebrated Constitution Day in your school.
3. Make a collection of the photos of the members of the Constituent Assembly.

Class 7 Civics Chapter 1 Introduction to Our Constitution InText Questions and Answers

In-text questions.

Question 1.
Do you wish to ask the questions that puzzled Sameer and Vandana?
Answer:
Yes, I wish to ask such questions.

Question 2.
Where can we find all the rules according to which the administration of the country is carried out?
Answer:
The rules according to which the administration of the country is carried out are found mentioned in a country’s constitution.

Question 3.
Who makes those rules?
Answer:
These rules are made by the Constituent Assembly which consist of the representatives of the states and provinces and the leaders of that country.

Question 4.
Is it binding on us to follow them?
Answer:
Yes. All the rules mentioned in the Constitution are binding on every citizen of the country.

Let’s find out:

Find out some information about the Constitution of any one country of your choice with the help of the following points.

Question 1.
Name of the country
Answer:
India

Question 2.
Year of the making of the Constitution:
Answer:
The Constituent Assembly enacted the Constitution and adopted it on 26th November 1949. However the country began to be actually governed according to the provisions of the Constitution only from 26th January 1950.

Question 3.
Two features of the Constitution:
Answer:
(a) The lengthiest Constitution in the world: The Indian Constitution is the lengthiest and the most detailed of all the written Constitutions of the world containing 449 articles in 25 parts, 12 schedules, 5 appendices and 101 Amendments.

(b) Parliamentary form of Government: The constitution of India establishes a parliamentary form of a government both at the Centre and the State. The essence of the parliamentary government is its responsibility to the Legislature. The President is the constitutional head of the State but the real executive power is vested in the council of ministers whose head is the Prime Minister.

Activity:

Question 1.
Several committees were established for the effective functioning of the constituent Assembly. Find out more information about them and discuss the role of different committees.
Answer:

1. Committee on the Rules of Procedure: Rajendra Prasad
2. Steering Committee : Rajendra Prasad
3. Finance and Staff Committee: Rajendra Prasad
4. Credential Committee: Alladi Krishnaswami Ayyar
5. House Committee: B. Pratibha Sitaramayya
6. Order of Business Committee: K.M. Munsi
7. Adhoc Committee on the National Flag: Rajendra Prasad
8. Committee on the Functions of the Constituent Assembly: G.V. Mavalankar
9. States Committee: Jawaharlal Nehru
10. Advisory Committee on Fundamental Rights, Minorities and Tribal and Excluded Areas:Vallabhbhai Patel
11. Minorities Sub-Committee: H. C. Mookherjee
12. Fundamental Rights Sub-Committee: J. B. Kripalani
13. North-East Frontier Tribal Areas and Assam Excluded & Partially Excluded Areas Sub¬Committee: Gopinath Bardoloi
14. Excluded and Partially Excluded Areas (Other than those in Assam) Sub-Committee: A.V. Thakkar
15. Union Powers Committee: Jawaharlal Nehru
16. Union Constitution Committee: Jawaharlal Nehru
17. Drafting Committee: B.R. Ambedkar

Class 7 Civics Chapter 1 Introduction to Our Constitution Additional Important Questions and Answers

Complete the sentence by choosing the appropriate words from the options given below:

Question 1.
The administration of our village or city is carried out in accordance with _______. (will of the majority, rules, orders of the Collector)
Answer:
rules

Question 2.
The book in which all the provisions regarding the administration of the country are mentioned together in a systematic way is called a ______ . (Law book, Guide, Constitution)
Answer:
Constitution

Question 3.
Democracy is _____ due to increased participation of the people. (strengthened, maintained, weakened)
Answer:
strengthened

Question 4.
The process of the making of the Indian Constitution started in the year _____. (1952,1947,1946)
Answer:
1946

Question 5.
A committee which was established to prepare the Constitution of independent India was the _______ (Drafting Committee, StandingCommittee, Constituent Assembly)
Answer:
Constituent Assembly

Question 6.
There were a total of ______ members in the Constituent Assembly. (298, 299, 289)
Answer:
299

Question 7.
_____ was the Chairman of the Drafting Committee. (Durgabai Deshmukh, J.B. Kripalani, Dr. Babasaheb Ambedkar)
Answer:
Dr. Babasaheb Ambedkar

Question 8.
Dr Babasaheb Ambedkar is called the ______ of the Indian Constitution’. (Architect, Visionary, Inspiration)
Answer:
Architect

Question 11
_____is observed as ‘Constitution Day’. (26th November, 26th January, 15th August)
Answer:
26th November

Question 10.
26th January is celebrated as ______ Day. (Independence, Republic, Constitution)
Answer:
Republic

Question 11.
Our Constitution is a/an _________ document of the provision related to the administration of the country. (written, oral, inspirational)
Answer:
written

Match the following:

Question 1.

(1) 15th August	(a) Constitution Day
(2) 26th November	(b) Republic Day
(3) 26th January	(c) Independence Day
(4) 26th January 1950	(d) Country began to be governed according to the provisions of the Constitution

Answer:
1 – c
2 – a
3 – b
4 – d

Answer in one or two sentences:

Question 1.
Why do we follow norms and rules?
Answer:
We follow norms and rules in order that the activities in the family, our school, our village or city are carried out smoothly.

Question 2.
How is the administration of our country carried out?
Answer:
The administration of our country is carried out through a system of rules.

Question 3.
Explain the term ‘Constitution’.
Answer:
The book in which all the provisions related to the administration of the country are mentioned together in a systemic way is called Constitution.

Question 4.
What are the basic or fundamental law of the land?
Answer:
The rules and provisions in the Constitution are the basic or fundamental law of the land.

Question 5.
How were decisions made in the Constituent Assembly?
Answer:
Decisions in the Constituent Assembly were made on the basis of debate and discussion.

Question 6.
What is governance?
Answer:
Government in modem times have to take decisions related to different issues right from space research to public cleanliness. This is governance.

Name the following:

Question 1.
Name the well-known members of the constituent assembly.
Answer:
Dr. Rajendra Prasad, Pandit Jawaharlal Nehru, Dr. Babasaheb Ambedkar, Sardar Vallabhbhai Patel, Maulana Abdul Kalam Azad, Sarojini Naidu, J. B. Kriplani, Rajkumari Amrit Kaur, Durgabai Deshmukh, Hansaben Mehta and others.

Question 2.
The President of the Constituent Assembly.
Answer:
Dr. Rajendra Prasad.

Question 3.
The States in pre-independence period where the local princes carried out the administration.
Answer:
Princely states.

Give reasons:

Question 1.
We celebrate 26th January as Republic Day.
Answer:
(i) Our country began to be governed according to the provisions of the Constitution from 26th January, 1950.

(ii) The Indian Republic came into existence from this day. Therefore, 26th January is celebrated as Republic Day.

Question 2.
Nature of the Constitutions of different countries is different.
Answer:

• There are differences of history, social structures, culture, traditions, etc., between the countries.
• Similarly, their needs and objectives also might be different.
• Each country tries to create a Constitution that is not only suited to its needs and objectives, but also is in tune with its distinct nature.

Explain in detail:

Question 1.
If the government does not follow the Constitution while making laws, the Judiciary can declare those laws null and void or unconstitutional. Explain.
Answer:

• The Government is established by the representatives elected by the people.
• It is bound to carry out the administration of the country as per the provisions of the Constitution.
• The rules and provisions in the Constitution are the basic or fundamental law of the land.
• While making laws, the government is bound to follow the Constitution.
• If it does not do so, then the Judiciary can declare those laws null and void or unconstitutional.

Question 2.
How long did it take to write the Constitution?
OR
Why is it the lengthiest Constitution in the world?
Answer:
(i) It took 2 years, 11 months and 17 days to ! complete the writing of the Constitution.

(ii) There were 22 parts, 395 Articles and 8 Schedules in the original Constitution, thus making it the lengthiest Constitution in the world.

Question 3.
Write about the wide range of issues in the Constitution which were contributed by Dr. Babasaheb Ambedkar.
Answer:
Dr. Babasaheb Ambedkar’s contribution was in a wide range of issues like water conservation, foreign policy, national security, journalism, economics, social justice, etc.

Question 4.
We are proud of our Constitution.
Answer:
(i) Decisions in the Constituent Assembly were made on the basis of debate and discussion. A respect for opposing view points and the acceptance of the appropriate suggestions were a characteristic of the working of the Constituent Assembly.

(ii) It took 2 years, 11 months and 17 days to complete the writing of the Constitution.

(iii) There were 22 parts, 395 Articles and 8 schedules in the original Constitution

Balbharti Maharashtra State Board Class 7 Geography Solutions Chapter 7 Soils Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Geography Solutions Chapter 7 Soils

Class 7 Geography Chapter 7 Soils Textbook Questions and Answers

1. Complete the following table.

Factor/Process	Role in the formation of soil
(1) Parent rock	…………….
(2) Regional climate	……………
(3) Organic material	…………..
(4) Micro­organisms	……………..

Answer:

Factor/Process	Role in the formation of soil
(1) Parent rock	The rock gets weathered depending on the hardness of the rock and the climate of the region. It turns into powdery material which further turns into soil.
(2) Regional climate	When the rock is exposed to a different climates, the same type of rock gives rise to different types of soil.
(3) Organic material	The organic material gets mixed into weathered powdery material and turn it into soil.
(4) Micro­organisms	Microorganisms help in decomposing the dead remains of organic materials and get mixed into the soil to form humus.

2. Why do the following occur?

Question 1.
To the west of Sahyadris, laterite soils are formed from the basalt rock.
Answer:

• Laterite soils are formed in regions of heavy rainfall.
• The climate of western Sahyadris is hot & humid.
• This leads to leaching of basalt rocks due to which there is formation of laterite soils.

Question 2.
Humus content in the soil increases.
Answer:

• Microorganisms and certain other organism help in decomposing the dead remains of organic materials.
• The biotic material thus produced is called humus.
• If organic manures, vermicompost compost are used regularly, the humus content in the soil increases.

Question 3.
Soil formation process is faster in the equatorial climate.
Answer:

• In the region of high rainfall and higher temperature the process of soil formation is faster.
• Equatorial climatic region have high temperature and receive high rainfall.
• Thus soil formation process is faster in the equatorial region.

Question 4.
The salinity of the soil increases.
Answer:

• Due to excessive irrigation, the salts from the soil are drawn upwards.
• This increases the salinity of the soil.

Question 5.
Rice is the staple diet of the people from Konkan.
Answer:

• Hot & humid climate, heavy rainfall & fertile alluvial soil are favourable for rice cultivation.
• This soil has good water holding capacity. Since these conditions are found in the konkan region, rice is grown on a large scale here.
• So rice is the staple diet of the people from Konkan.

3. Give information on:

Question 1.
Measures of soil conservation
Answer:
The following are the measures of soil conservation:

(i) Afforestation / Planting trees: Planting trees can control the velocity of wind. This helps reducing erosion by wind. The plant roots hold the soil and also reduces the erosion of soil.

(ii) Continuous contour trenches: Construction of continuous contour trenches at different height checks the velocity of water running along the slopes & hence reduces soil erosion. The water arrested in these trenches percolates into the ground.

(iii) Implementation of watershed Development program: The Government of Maharashtra has implemented the watershed development programme under which constructing embankment along slopes in rural areas, introducing CCTs along steep slopes etc. are undertaken. This led to the success of the scheme ‘Arrest water, let it percolate’. This has resulted in raising the ground water levels & reducing the erosion of soil.

(iv) Implementation of Jalayukt Shivar: Under the scheme of Jalayukt Shivar, works like construction of farm bunds, arresting waters of small streams, connecting the streams etc. are being carried out on a large scale.

Question 2.
Organic Manures.
Answer:
(i) Organic manures in farming, helps to maintain the pH balance.
(ii) It also increases the proportion of humus, and retain the fertility of soil.

Question 3.
Place where you will get the information about the suitability of a soil for a particular crop.
Answer:
(i) The information about the suitability of a soil can be obtained from Department of Agriculture of Government of Maharashtra, Natural Resource conservation services, soil testing laboratories in various states and at many agricultural universities.

(ii) The type of soil, soil fertility, pH status of the soil, etc. are determined in soil testing.

(iii) Based on the testing, an analysis of the soil is done & information about the suitability of a soil for a particular crop is provided.

Question 4.
Importance of soils for plant growth.
Answer:
(i) Soil is important for plant as it hold roots that provide support for plants and stores nutrient for the growth of plants.
(ii) Fertile soils favour plant growth.

4. Complete the following table with reference to soil.

Action	Effect	Result (W.R.T. fertility)
Construction of embankments.
	Wind speed decreased.
Farm land is kept fallow for some period.	Helps to maintain the pH balance and increase the proportion of humus.	Increases the fertility of soil.
Regular use of organic manures, vermicompost and compost.
	Check the velocity of water running along the slopes.
Litter is burnt in the farm.
Decomposed vegetal litters, roots of plants and remains of animals.
	Salt content in the soil increases.
	Leads to the lowering of humus content in the soil.

Answer:

Action	Effect	Result (W.R.T. fertility)
Construction of embankments.	Protects soil from being washed away.	Protects fertility of soil.
Planting trees.	Wind speed decreased.	Protects fertility of soil
Farm land is kept fallow for some period.	Helps to maintain the pH balance and increase the proportion of humus.	Increases the fertility of soil.
Regular use of organic manures, vermicompost[1] and compost.	Humus content increased.	Increases the fertility of soil.
Trenches are dug across a slope.	Check the velocity of water running along the slopes.	Protects fertility of soil
Litter is burnt in the farm.	Decreases the amount of organic material in soil.	Decreases the fertility of soil.
Decomposed vegetal litters, roots of plants and remains of animals.	Proves favourable for micro organism.	Increases the fertility of soil.
Excessive Irrigation	Salt content in the soil increases.	Decreases the fertility of soil
Chemical fertilizers used excessively.	Leads to the lowering of humus content in the soil.	Decreases the fertility of soil

Activity:

1. Visit a soil testing centre/laboratory and note the work that is carried out in the centre.
2. Prepare compost at home or in your housing society.
3. Visit a place where ‘Arrest water, let it percolate’ is being implemented. Collect information about it and make a note of it.

Class 7 Geography Chapter 7 Soils InText Questions and Answers

Think about it:

Question 1.
Rohit and Prateeksha noted that their field had yielded a bumper crop. But they also noted that a part of their field had a stunted growth of plants. What investigation will you suggest to them?
Answer:
I would suggest that they should check whether organic manures, are used evenly on all the parts of the field. Also, they should check whether that part of the field is getting adequate supply of water or not.

Question 2.
Why do equatorial regions have fertile soils?
Answer:
The sun rays are perpendicular in equatorial
regions so the climate is very hot and humid. This region also receives very heavy rainfall. As the process of soil formation is faster in these regions, equatorial regions have fertile soil. Also vegetal litter roots of plants, remains of animals, etc.; get decomposed adding to soil fertility.

Question 3.
Why is the vegetation sparse in deserts?
Answer:
A desert is a barren area of land where a little precipitation occurs and consequently living conditions for plant and animal life are very hostile. It is an area where the soils are not fertile & hence vegetation is scanty.

Try this:

• Take three flower pots of the same size.
• Keep one pot empty. Fill the second pot. With water after closing the hole at the bottom and fill the third pot with soil.
• Put a few seeds in all of them. (You may use aserio, peas, gram, fenugreek, wheat, green gram, coriander seeds, etc.)
• Keep all the three pots in the sun. and water the empty pot and the soil-filled pot for 4-5 days. Observe and answer the following.

Question 1.
What happened to the seeds put in the empty pot and pot filled with water?
Answer:
Seeds in the empty pot and the pot filled with water did not germinate and did not show any sign of growth.

Question 2.
What happened to the seeds put in the pot (c) filled with soil?
Answer:
Seeds germinated and we could see some small twigs branching out.

Question 3.
What do you learn from this?
Answer:
We learn that plants need sunlight, water and soil to grow.

Class 7 Geography Chapter 7 Soils Additional Important Questions and Answers

Fill in the blanks:

Question 1.
_____ rock in a region is an important factor in soil. (Parent, Basalt, Granite)
Answer:
Parent

Question 2.
The process of weathering depends on the _____ of the region. (climate, weather, soil)
Answer:
climate

Question 3.
The _____ rock of the Deccan Plateau in Maharashtra turns into black soil after weathering. (granite, basalt, parent)
Answer:
basalt

Question 4.
______ soils along the river beds give higher yields. (Infertile, Fertile, Coarse)
Answer:
Fertile

Question 5.
The _____ material comes from the decomposition of the remains of the plants and animals in that region. (biotic1, abiotic, pH)
Answer:
biotic1

Question 6.
______ is a complete ecosystem.(Soil, Humus, weathered rocks)
Answer:
Soil

Question 7.
Food crops like jowar and bajra are produced in the _____ soils of Maharashtra Plateau. (regur, coarse, laterite)
Answer:
regur

Question 8.
The local agriculture produce determines the _______ diet of the people. (staple, supplementary, secondary)
Answer:
staple

Question 9.
The proportion of humus is negligible in _____ soil. (coarse, black, laterite)
Answer:
coarse

Question 10.
Planting trees can also control the _____ of the wind. (velocity, direction, temperature)
Answer:
velocity

Question 11.
Rocks like granite or gneiss in South India give rise to ____ soil. (black, red, regur)
Answer:
red

Question 12.
In the humid climate of western Sahyadris the leaching of basalt rocks leads to formation of ___ soil. (black, lateritic, red)
Answer:
lateritic

Question 13.
The excessive spraying of chemicals and use of chemical fertilizers lead to ______; (soil degradation soil fertility, soil powder)
Answer:
soil degradation

Complete the following sentences:

Question 1.
The biotic material comes from _____.
Answer:
the decomposition of the remains of the plants and animals in that region

Question 2
Microorganisms ajnd certain other organisms help decompose the dead remains of ______.
Answer:
organic materials

Question 3.
Production of compost needs sufficient period of time and ______.
Answer:
elements like organic waste, water, heat, etc.

Question 4.
In the region of high rainfall and higher temperatures, _____.
Answer:
the process of soil formation is faster

Question 5.
In regions of low temperatures and low rainfall the _____.
Answer:
soil formation takes more time

Question 6.
High use of chemical fertilizers, insecticides _____.
Answer:
leads to the degradation of soils

Question 7.
In the areas where the soil is not fertile, _______.
Answer:
egetation is scanty

Question 8.
When man realized that sowing of seeds in the soil leads to the growth of plants and yields crops, ______.
Answer:
he started using soil as a resource

Question 9.
Excessive irrigation draws the salts from the soil upwards and ______.
Answer:
makes the soil saline and then unproductive

Question 10.
Keeping the farmland fallow for some period and cultivating different crops alternatively is important ________.
Answer:
to help retain the fertility of soils.

Give one word for the following:

Question 1.
Soil formed due to weathering of basalt rock.
Answer:
Black soil

Question 2
Soil formed due to the leaching of the basalt rock.
Answer:
Lateritic soil

Question 3.
Biotic material mixed into the soils.
Answer:
Humus

Question 4.
The excessive spraying of chemicals and use of chemical fertilizers.
Answer:
Soil degradation

Question 5.
The govt, scheme, work like construction of farm bunds, arresting waters of small streams, etc.
Answer:
Jalayukt Shivar.

Who am I?

Question 1.
I am a very important rock factor in soil formation.
Answer:
Parent rock

Question 2
I form due to weathering of basalt rock. Jowar and Bajra mostly grow on this soil.
Answer:
Regur soil / Black soil

Question 3.
I am found in the hilltops of the western part of the Deccan plateau.
Answer:
Coarse soil

Question 4.
I am black in colour and have less organic components.
Answer:
Regur or Black soil

Question 5.
I am orange in colour and mostly found in the coastal belt of Konkan.
Laterite soil

Question 6.
I am found at the mouth of the river in the western coastal strip.
Answer:
Alluvial soil of the coastal strip

Question 7.
I am mainly found in areas of extreme rainfall but not very useful for agriculture.
Answer:
Yellow brown soil

Question 8.
I am a method of soil conservation which controls the velocity of wind.
Answer:
Afforestation / planting trees

Match the columns:

Question 1.

Column I	Column II
(1) Coarse soil	(a) Alluvium deposition
(2) Regur soil	(b) Eastern part of Bhandara
(3) Laterite soil	(c) Ajanta, Balaghat, Mahaden hills
(4) Alluvial soil	(d) Coastal belt of konkan
(5) Yellow-brown soil	(e) Weathering of basalt rock

Answer:
1 – c
2 – e
3 – d
4 – a
5 – b

Answer the following questions in short:

Question 1.
What do you mean by ‘Soil’?
Answer:
(i) The uppermost layer of the earth’s crust is called ‘Soil’.
(ii) It contains the organic as well as mineral matter necessary for the growth of plants.

Question 2
What are the factors necessary for the soil formation?
Answer:
Soil is formed by:

• Weathering of the parent rock material.
• Climatic conditions of the region.
• The decomposition of plant remains.
• Animal manures and dead animals.
• Very long period of time.

Question 3.
What is leaching ?
Answer:
(i) Leaching is a process is which the salts & other soluble material are washed out of the rock through percolation of water.
(ii) This process is dominant in the areas of high rainfall & humid climate.

Question 4.
What is Humus?
Answer:
(i) The decaying of organic material such as dead leaves, stems, root of the plant, vegetal litters, decomposed remains of animals get mixed into the soil.
(ii) This results in the formation of “Humus” thus retaining the fertility of soil.
(iii) If the proportion of humus in the soil is greater, the soil becomes fertile.

Question 5.
What leads to the degradation of soils?
Answer:
(i) For getting higher production, different types of chemical fertilizers, insecticides are used profusely.
(ii) This leads to the degradation of soils.

Question 6.
What led to record agricultural production?
Ans,
(i) To get richer harvests man made efforts to increase the fertility of soils.
(ii) In the process, use of different fertilizers became a practice which led to record agricultural production.

Question 7.
What is soil erosion?
Answer:
(i) When a layer of soil (top layer of soil) get removed due to wind or water it is called soil erosion.
(ii) Running water, climate and diversity in physiography are the reasons of soil erosion.

Question 8.
What helps to maintain the pH balance of the soil?
Answer:
(i) Organic manures, vermicompost, compost are used regularly.
(ii) It helps in maintaining the pH balance and retaining the fertility of the soil.

Why do the following occur:

Question 1.
Rice is the staple diet of the people from Konkan.
Answer:
(i) Hot & humid climate, heavy rainfall & fertile alluvial soil are favourable for rice cultivation.
(ii) This soil has good water holding capacity. Since these conditions are found in the konkan region, rice is grown on a large scale here.
(iii) So rice is the staple diet of the people from Konkan.

Question 2.
Soil Erosion.
(i) A layer of soil gets removed due to wind or water.
(ii) Running water, climate and diversity in physiography are the reasons of soil erosion.

Question 3.
Soil degradation.
Answer:
(i) To obtain a higher agricultural yield, chemical fertilizers, insecticides, weedicides, etc. are used.
(ii) The excessive spraying of chemicals and use of chemical fertilizers leads to soil degradation.

Give geographical reasons:

Question 1.
Planting trees is necessary to conserve the soil.
Answer:
(i) A layer of soil gets removed due to wind or water which leads to soil erosion.
(ii) Planting trees controls the velocity of the wind, thus reducing the erosion of soil by wind.
(iii) The roots of the plants hold the soil which also prevents soil erosion.

Question 2
Continuous contour trenches are constructed along the slopes.
Answer:
(i) Construction of continuous contour trenches (CCTs) at different heights checks the velocity of water running along the slopes.
(ii) This reduces soil erosion.

Question 3.
It is advisable to use organic manures, vermicompost and compost regularly.
Answer:
(i) Use of organic manures, vermicompost, compost helps maintain the pH balance.
(ii) It also increases the proportion of humus thus retaining the fertility of soil.
(iii) Hence, it is advisable to use organic manures, vermicompost & compost regularly.

Question 4.
There emerged competition among the people to discover fertile lands and settle there.
Answer:
(i) Man started producing greater amount of food crops for the growing population.
(ii) He realized that crop production and prosperity in agriculture depends on the fertility of soil and the optimum availability of water.
Hence, there emerged competition among the people to discover fertile lands & settle there.

Question 5.
There was a rise of Indus civilization.
Answer:
(i) When man realized that the fertile soils along the river beds give higher yields.
(ii) He settled in the valleys and started living there in groups.
(iii) This led to the rise of Indus civilization.

Question 6.
Countries like Saudi Arabia, Qatar, Oman, etc., fulfil their requirements by importing food from other countries.
Answer:
(i) In countries like Saudi Arabia, Qatar, Oman etc. the soils are not arable so there is need to fulfil their food requirement.
(ii) Hence, countries like Saudi Arabia, Qatar, Oman import food from other countries.

Question 7.
Lets find the names of the soils we have learnt and which regions they are found?
Answer:

Soils	Answers	Regions
(1) RUGER	Regur	(a) Western part of Deccan Plateau and eastern part of Vidarbha.
(2) LUILALVA	Alluvial	(b) Panvel, Uran Coast, Dharamtar creek.
(3) OARCSE	Coarse	(c) Ajanta, Balaghat and Mahadeo hills.
(4) AEILTRITE	Laterite	(d) Coastal belt of Konkan, West of Sahyadris and East of Vidarbha.

Make Friends with maps!
Observe the map given below and answer the following questions:

Question 1.
Which soil occupies most of the areas in Maharashtra?
Answer:
Black (Regur) soil occupies most of the areas in Maharashtra.

Question 2
In which areas are laterite soils found?
Answer:
Laterite soil is found in Raigad, Ratnagiri,Sindhudurg and some parts of Gadchiroli and Nashik.

Question 3.
Which soil is found in parts of the Sahyadri ranges?
Answer:
Yellow Brown soil is found in parts of the Sahyadri ranges.

Question 4.
In which region is alluvial soil found?
Answer:
Alluvial soil is found in Mumbai Suburban District, Mumbai city district some parts of Thane & Palghar district.

Question 5.
Which soil is found in the river valleys of Maharashtra?
Answer:
Fertile Alluvial Soil is found in the river valleys of Maharashtra.

Balbharti Maharashtra State Board Class 7 Geography Solutions Chapter 11 Contour Maps and Landforms Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Geography Solutions Chapter 11 Contour Maps and Landforms

Class 7 Geography Chapter 11 Contour Maps and Landforms Textbook Questions and Answers

1. Answer the following questions:

Question 1.
How can the distribution of the height and landform in a region be shown?
Answer:
(i) While studying different landforms on the surface of the earth, one has to consider various facets of landforms like altitude, relief, slope, direction of slope and the drainage.
(ii) For this maps prepared using mathematical survey methods are used.
(iii) These maps help us to understand the above characteristics of the landforms.

Question 2.
To whom are contour maps useful?
Answer:
(i) Contour maps are useful to mountaineers, trekkers, soldiers, defence officers.
(ii) The nature of the ground and its shape can be estimated .
(iii) Defence officers use contour maps for strategic planning.
(iv) It is possible to identify suitable site for any project from the contour map of the region.

Question 3.
What do you understand by observing contour lines?
Answer:
(i) Contour lines are isolines of height.
(ii) These are drawn by joining the places of equal altitude.
(iii) These help in identification of land forms and their altitude from sea level.
(iv) These lines also help us to understand the nature and direction of the slope.

Question 4.
How will a contour map be useful to a fanner?
Answer:
(i) It is helpful selecting the type of farming to be practiced plantation farming in hilly regions, intensive farming in low lying region.
(ii) In order to reduce the erosion of soil, trenches are dug out in the direction perpendicular to the slope of the land.
(iii) Trees are planted along such trenches. When the farmer digs out such trenches, he will be careful in maintaining the level.

2. Fill the blanks with appropriate words:

Question 1.
If the contour lines are closer to each other, the slope is ______.
Answer:
steep

Question 2.
The contour lines on the map represent ______.
Answer:
places of same altitude

Question 3.
The slope can be understood from the distance between the ______.
Answer:
contour lines

Question 4.
If the distance between two contour lines is more then the ______ is gentle.
Answer:
slope

3. Identify the landforms in the following map:

Class 7 Geography Chapter 11 Contour Maps and Landforms InText Questions and Answers

A model of the relief in an area is shown in fig. Observe it carefully and answer the following questions:

Question 1.
Which landforms do you seen in the model?
Answer:
Mountains & river valleys are seen in the model.

Question 2.
Which colours have been used on them?
Answer:
Yellow & blue colours have been used in the model.

Model of the Earth’s surface:

Question 1.
What all you seen in the map?
Answer:
We can see many contour lines on the map showing a hilly region. We can see the altitude of the hill ranges as well as its slope.

Question 2.
What is the general direction of the ranges shown in the map?
Answer:
The general direction of the ranges shown in the map is east-west

Question 3.
Towards which direction is the flat land located in the map?
Answer:
The flat land is located towards the east.

Question 4.
What are the maximum and minimum values of the lines in the map?
Answer:
The maximum value of the lines in the map is 800 & minimum value is 600.

Question 5.
What do these values indicate?
Answer:
These lines indicate the altitude of the region from the sea level.

Question 6.
Do you find any similarities in the map and the model in fig. (a)? What are those?
Answer:
The model in figure (a) & the contour line map in figure (b) are of the same region. The values of latitudes & longitudes are same on both the maps.

Question 7.
Which figure give us more information and what is that information?
Answer:
Fig. (b) Contour line map gives more information. It gives us information about the altitude of the landforms slope of the land forms with latitudes & longitudes

Question 8.
Is there any similarity between this map and the sketch map of the potato hill?
Answer:
Yes, similar to the sketch map of the potato hill,
the contour line map too is a 3D figure (Model of earth’s surface) which has been converted into a 2D map. The Contour line map is depicting contour line intervals.

Consider you have gone for mountaineering. You have to conquer a peak on the hill “A”. A map of this hill is given below. Studying the contour lines in the map, find the side from which you will reach the peak safely and easily. Mark your path on the map with a pencil.

Answer:
I will climb from eastwards to reach the peak safely as the slope eastwards is gentle and not steep. Lesser distance between the contour lines, indicates steep slope. The distance between the lines is greater eastwards, which shows the slope is more gentle on that side.

Class 7 Geography Chapter 11 Contour Maps and Landforms Additional Important Questions and Answers

Fill in the blanks:

Question 1.
Contour lines join places with the same on a map.
Answer:
altitude

Question 2.
Generally, contour lines do not _______ each other.
Answer:
cross.

Answer the following questions:

Question 1.
How are contour maps helpful to us?
Answer:
(i) Contour maps help us to understand various facets of landforms, like altitude, relief, slope, direction of slope and the drainage.
(ii) These maps are of immense use to mountaineers, trekkers, soldiers, defence officers, etc.
(iii) These maps prove to be of great use in planning of a region.

Question 2.
Contour lines generally do not cross each other. Give reason.
Answer:
(i) Contour lines join places with the same altitude on a map.
(ii) Therefore they generally do not cross each other.

Observe the model and the map given below and answer the following questions:

A 3D model is given in fig. (a) The northern part of the model shows the basin of the rivers Mula-Mutha. To its south is the Katraj. Diveghat range extending from the west to the east. Beyond that some portion of Karha basin is seen.

Question 1.
In which direction does fort Purandar lie?
Answer:
Fort Purandar lies in the south direction.

Question 2.
What is the direction of flow of the river Karha?
Answer:
River Karha flows from west to east.

Question 3.
In which parts are the hill ranges not observed?
Answer:
The hill ranges are not observed in the eastern parts.

Question 4.
Which part of the model is not seen in the map? Why?
Answer:
The Karha river & the direction of its flow, the contour height and the slope of the land are part of map & not seen in the model.

Question 5.
In which direction does the altitude of Katraj- Diveghat range decrease?
Answer:
The altitude of katraj-Diveghat range decreases from west to east.

Question 6.
In which direction are higher hill ranges located?
Answer:
Higher hill ranges are located in the southern direction.

Use your brain!

When one sees a landform on a contour map, what is the observer’s position with respect to landform? For example, a hill is shown with the help of contours on a map. From where do you think you are looking at it?
Answer:
Aerial view. From somewhere above, may be from an aeroplane or helicopter.

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 5 Inside the Atom Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 8 Science Solutions Chapter 5 Inside the Atom

Class 8 Science Chapter 5 Inside the Atom Textbook Questions and Answers

1. Answer the following.

Question a.
What is the difference in the atomic models of Thomson and Rutherford?
Answer:

Thomson’s atomic model	Rutherford’s atomic model
1. According to Thomson’s atomic model, the negatively charged electrons are embedded in a gel of positive charge.	1. According to Rutherford’s atomic model the negatively charged electrons revolve around the nucleus.
2. Atom is homogenous sphere of positive charge.	2. The positive charge is in the nucleus of the atom.

Question b.
What is meant by valency of an element? What is the relationship between the number of valence electron and valency?
Answer:
Valency: The capacity of an ; element to combine with another element is known as valency.
Valence electrons: The electrons in the outermost shell of an atom of an element are called valence electrons.
Helium and neon, atoms of both these gaseous element do not combine with any other atom. These elements are chemically inert, i.e. their valency is zero.

Helium atom contains two electrons, indicates that the outermost shell of helium has an electron duplet. The valence shell of neon is completely filled, i.e. neon has an electron octet. Similarly argon contains eight electrons in the valence shell, i.e. argon has an electron octet. It is confirmed that the valency is zero when electron octet (or duplet) is complete.

Atoms of all the elements except inert gases have tendency to combine with other atoms, i.e. they have a non zero valency. The molecules formed by combination with hydrogen (E.g. H₂, HCl) that valency of hydrogen is one. The electronic configuration of hydrogen shows that there is one electron less than the complete duplet state. This number ‘one’ matches with the valency of hydrogen which is also one.

It means that there is relationship between the valency of an element and the number of electrons in its valence shell.

Question c.
What is meant by atomic mass i number? Explain how the atomic number and mass number of carbon are 6 and 12 respectively.
Answer:
The total number of protons and neutrons in the nucleus of the atom is called the atomic mass number. The atomic number, i.e. the proton number of carbon is 6 and the mass number is total number of protons and neutrons in the carbon, i.e. 6 protons + 6 neutrons = 12. Therefore, the atomic number and mass number of carbon are 6 and 12 respectively.

Question d.
What is meant by subatomic particle? Give brief information of three subatomic particles with reference to electrical charge, mass and location.
Answer:
A particle which is a constituent of an atom hence smaller than the atom is called subatomic particle.
An atom is formed from the nucleus and the extranuclear part. These contain three types of subatomic particles.
The nucleus contains two types of subatomic particles together called nucleons. Protons and neutrons are the two types of nucleons or subatomic particles and electrons are subatomic particles in the extra nuclear part.

1. Proton (p): Proton is a positively charged subatomic particle in the atomic nucleus. The positive charge on the nucleus is due to the proton in it. A proton is represented by the symbol ‘p’. Each proton carries a positive charge of +1e. (1e = 1.6 × 10^-19 coulomb). When total positive charge on the nucleus is expressed in the unit ‘e’, its magnitude is equal to the number of proton in the nucleus.
The mass of one proton is approximately lu (1 Dalton).
(1u = 1.66 × 10^-27g) (The mass of one hydrogen atom is also approximately lu.)

2. Neutron (n): Neutron is an electrically neutral subatomic particle and is denoted by the symbol ‘n’. The number of neutron in the nucleus is denoted by the symbol ‘N’ Atomic nuclei of all the elements except hydrogen with atomic mass lu, contain neutrons. The mass of a neutron is approximately lu, which is almost equal to that of a proton.

3. Electron (e^–): Electron is a negatively charged subatomic particle and is denoted by the symbol ‘e-’. Each electron carries one unit of negative charge (-1e). Mass of an electron is 1800 times less than that of a hydrogen atom. Therefore the mass of an electron can be treated as negligible. Electron in the extranuclear part revolve in the discrete orbits around the nucleus. The energy of an electron is determined by the shell in which it is present.

2. Give scientific reasons:

Question a.
All the mass of an atom is concentrated in the nucleus.
Answer:

1. The nucleus of an atom contains protons and neutrons.
2. The electrons revolve around the nucleus.
3. The mass of an electron is negligible compared to that of a proton or a neutron.
4. Hence, the mass of an atom depends mainly on the number of protons and neutrons. Therefore, practically all the mass of an atom is concentrated in the nucleus.

Question b.
Atom is electrically neutral.
Answer:

1. An atom is made of two parts, viz. the nucleus and the extranuclear part.
2. The nucleus is positively charged. The positive charge on the nucleus is due to protons.
3. The extranuclear part of an atom is made of negatively charged electrons.
4. In an atom, the number of protons is equal to the number of extranuclear electrons.
5. The magnitude of the positive charge on the nucleus equals the magnitude of the negative charge on the electrons. As the opposite charges are balanced, the atom is electrically neutral.

Question c.
Atomic mass number is a whole number.
Answer:

1. The total number of protons and neutrons in the nucleus of the atom is called the atomic mass number (A).
2. As protons and neutrons are whole numbers, the atomic mass number is also a whole number.

Question d.
Atoms are stable though negatively charged electron are revolving within it.
Answer:

1. The entire mass of the atom is concentrated in the nucleus and the positively charged nucleus at centre of an atom.
2. The negatively charged electrons revolve around the nucleus.
3. The total negative charge on all the electron is equal to positive charge on the nucleus. As the opposite charges are balanced, the atom is stable.

3. Define the following terms.

Question a.
Atom:
Answer:
An atom is the smallest particle of an element which retains its chemical identity in all physical and chemical changes.

Question b.
Isotope
Answer:
Atoms of the same element having the same atomic number, but different atomic mass numbers are called isotopes.

Question c.
Atomic number
Answer:
The number of electrons or protons in an atom is called the atomic number. It is denoted by Z.

Question d.
Atomic mass number
Answer:
The total number of protons and neutrons in the nucleus of the atom is called the atomic mass number. It is denoted by A.

Question e.
Moderator in nuclear reactor
Answer:
The substance which reduces the speed of fast-moving neutrons produced in a fission is called a moderator.

4. Draw a neal labelled diagram.

Question a.
Explain Rutherford’s scattering experiment.
Answer:

Alpha particles emitted by radioactive element bear a positive charge. Rutherford bombarded alpha particles through a very thin gold foil. He observed the path of α – particles by means of a fluorescent screen around the gold foil. It was expected that

1. Most of the alpha particles passed through the gold foil without any deviation.
2. Some alpha particles were deflected from their path through small angles.
3. A few alpha particles were scattered at large angles.
4. A still smaller number of same sign particles get deflected through a larger angle and one a-particle out of 20000 bounced back in the direction opposite to the original path.

Question b.
Thomson’s atomic model.
Answer:
Thomson’s plum pudding model of atom:

1. According to Thomson’s model the positive charge is distributed throughout the atom and the negatively charged electron: are embedded in a gel of positive charge (a plum pudding model).
2. The distributed positive charge is balanced by the negative charge on the electrons. Therefore the atom becomes electrically neutral.

Question c.
Diagrammatic sketch of electronic configuration of magnesium (Atomic number 12).
Answer:

Question d.
Diagrammatic sketch of electronic configuration of argon (Atomic number 18).
Answer:

5. Fill in the blanks.

Question 1.
Electron, proton, neutron are the types of ………… in an atom.
Answer:
Electron, proton, neutron are the types of subatomic particles in an atom.

Question 2.
An electron carries a ……………. charge.
Answer:
An electron carries a negative charge.

Question 3.
The electron shell ………….. is nearest to the nucleus.
Answer:
The electron shell K is nearest to the nucleus.

Question 4.
The electronic configuration of magnesium is 2, 8, 2. From this it is understood that the valence shell of Magnesium is …………….. .
Answer:
The electronic configuration of magnesium is 2, 8, 2. From this it is understood that the valence shell of Magnesium is M.

Question 5.
The valency of hydrogen is one as per the molecular formula H₂O. Therefore valency of ‘Fe’ turns out to be ………….. as per the formula Fe₂O₃.
Answer:
The valency of hydrogen is ‘one’ as per the molecular formula H₂O. Therefore valency of ‘Fe’ turns out to be 3 as per the formula Fe₂O₃.

6. Match the pairs.

Question 1.

Column I	Column II
1. Proton	a. Negatively charged
2. Electron	b. Neutral
3.  Neutron	c. Positively charged

Answer:

Column I	Column II
1. Proton	c. Positively charged
2. Electron	a. Negatively charged
3. Neutron	b. Neutral

7. Deduce from the datum provided.

Question 1.

Answer:
1. There are 12 neutrons in the sodium \(\left({ }_{11}^{23} \mathrm{Na}\right)\).
(N = A – Z) 23 – 11 = 12
2. Atomic mass number of \({ }_{6}^{14} \mathrm{C}\) is 14.
3. There are 17 protons in chlorine \(\left({ }_{37}^{17} \mathrm{Cl}\right)\)

Project:

Explain the atomic models using the material such as old C.D., balloon, thread, marbles, etc.

Class 8 Science Chapter 5 Inside the Atom Additional Important Questions and Answers

Rewrite the sentences after filling the blanks:

Question 1.
An atom is electrically ……………. .
Answer:
An atom is electrically neutral.

Question 2.
Except hydrogen, the nuclei of all atoms contain ………….. .
Answer:
Except hydrogen, the nuclei of all atoms contain neutrons.

Question 3.
\({ }_{6}^{12} \mathrm{C}\), …………… and …………. are isotopes of carbon.
Answer:
\({ }_{6}^{12} \mathrm{C}\), \({ }_{6}^{13} \mathrm{C}\) and \({ }_{6}^{14} \mathrm{C}\) are isotopes of carbon.

Question 4.
An atom has 11 protons and …………. neutrons and hence its atomic mass number is 23.
Answer:
An atom has 11 protons and 12 neutrons and hence its atomic mass number is 23.

Question 5.
The element ………….. has two electrons in the K shell, but it is a noble gas.
Answer:
The element helium has two electrons in the K shell, but it is a noble gas.

Question 6.
Isotopes of the element have the same ……….. properties.
Answer:
Isotopes of the element have the same chemical properties.

Question 7.
Electrons must absorb …………….. to transit between orbits.
Answer:
Electrons must absorb energy to transit between orbits.

Question 8.
……….. discovered the electron.
Answer:
J. J. Thomson discovered the electron.

Question 9.
∝ – particles have ………….. charge.
Answer:
∝ – particles have positive charge.

Question 10.
Electrons revolve around the …………….. in certain discrete orbits.
Answer:
Electrons revolve around the nucleus in certain discrete orbits.

Question 11.
The shell-wise distribution of electrons is called the ………………… .
Answer:
The shell-wise distribution of electrons is called the electronic configuration.

Question 12.
Democritus termed the smallest particles of matter as …………… .
Answer:
Democritus termed the smallest particles of matter as atoms.

Question 13.
………………. discovered neutron.
Answer:
James Chadwick discovered neutron.

Question 14.
Electrons revolve around the nucleus in paths called ………….. .
Answer:
Electrons revolve around the nucleus in paths called orbits.

Question 15.
The second shell has the capacity of ……………… .
Answer:
The second shell has the capacity of 8 electrons.

Question 16.
Electrons in the ………….. shell have minimum energy.
Answer:
Electrons in the K or first shell have minimum energy.

Question 17.
Electrons in an atom occupy shells in increasing order of …………… .
Answer:
Electrons in an atom occupy shells in increasing order of energy.

Question 18.
Atomic masses are measured in a unit called …………… .
Answer:
Atomic masses are measured in a unit called dalton.

Question 19.
According to the atomic model of …………….., electrons are embedded in a gel of positive charge.
Answer:
According to the atomic model of Thomson, electrons are embedded in a gel of positive charge.

Question 20.
All atoms, except ………….. contain neutrons in their nuclei.
Answer:
All atoms, except normal hydrogen contain neutrons in their nuclei.

Question 21.
The maximum capacity of the M shell is ………………… electrons.
Answer:
The maximum capacity of the M shell is 18 electrons.

Question 22.
The atom of the element ……………. has eight electrons in the outermost shell.
Answer:
The atom of the element neon has eight electrons in the outermost shell.

Rewrite the following statements selecting the correct options:

Question 1.
The symbol A is used to denote the …………. .
(a) atomic number
(b) atomic radius
(c) atomic mass number
(d) atomic mass
Answer:
(c) atomic mass number

Question 2.
The existence of isotopes is due to the presence of different number of …………….. .
(a) electrons
(b) protons
(c) neutrons
(d) positrons
Answer:
(c) neutrons

Question 3.
In the nucleus of a sodium atom (\({ }_{11}^{23} \mathrm{Na}\)), there are ……………… neutrons.
(a) 11
(b) 12
(c) 10
(d) 9
Answer:
(b) 12

Question 4.
Isotopes of an element have the same number of …………….. .
(a) neutrons
(b) nucleons
(c) electrons
(d) atoms
Answer:
(c) electrons

Question 5.
The great Indian philosopher ………….. proposed that matter is made up of invisible tiny particles.
(a) Aryabhatta
(b) Kanad
(c) Bhaskaracharya
(d) Chanakya
Answer:
(b) Kanad

Question 6.
The maximum capacity of the M shell is …………… electrons.
(a) 2
(b) 8
(c) 18
(d) 32
Answer:
(c) 18

Question 7.
The mass of the electron is …………….. times less than that of a hydrogen atom.
(a) 1800
(b) 8100
(c) 1550
(d) 1600
Answer:
(a) 1800

Question 8.
The L shell is the valence shell in …………. .
(a) hydrogen
(b) chlorine
(c) oxygen
(d) sodium
Answer:
(c) oxygen

Question 9.
The M shell is the valence shell in ……………….. .
(a) fluorine
(b) neon
(c) carbon
(d) chlorine
Answer:
(d) chlorine

Question 10.
The N shell is the valence shell in ………….. .
(a) fluorine
(b) chlorine
(c) bromine
(d) helium
Answer:
(c) bromine

Question 11.
The maximum capacity of the N shell is ……………. electrons.
(a) 2
(b) 32
(c) 18
(d) 8
Answer:
(b) 32

Question 12.
The maximum number of electrons that can be accommodated in the third orbit is ………… .
(a) 3
(b) 8
(c) 32
(d) 18
Answer:
(d) 18

Question 13.
Rutherford alpha-particle scattering experiment was responsible for the discovery of the ………………. .
(a) atomic nucleus
(b) proton
(c) electron
(d) atomic mass
Answer:
(d) atomic mass

Question 14.
Isotopes of element have …………….. .
(a) different atomic numbers and different atomic mass
(b) different atomic numbers but the same atomic mass number
(c) the same atomic number but different atomic mass numbers
(d) the same atomic number and the same atomic mass number
Answer:
(c) the same atomic number but different atomic mass numbers

Question 15.
The nucleus of an atom contains 19 protons and 21 neutrons. The atomic mass number of the element is ………….. .
(a) 19
(b) 21
(c) 40
(d) 39
Answer:
(c) 40

Question 16.
The nucleus of an atom contains 18 protons and 22 neutrons. The atomic number of the element is ……………… .
(a) 18
(b) 40
(c) 22
(d) 4
Answer:
(a) 18

Question 17.
When writing the symbol of its …………… and ………….. are written.
(a) atomic number, atomic mass number
(b) protons, electrons
(c) protons, neutrons
(d) atomic number, electrons
Answer:
(a) atomic number, atomic mass number

Question 18.
The particles in the atomic nucleus are …………….. .
(a) protons and electrons
(b) electrons
(c) electrons and neutrons
(d) protons and neutrons
Answer:
(d) protons and neutrons

State whether the following statements are True or False:

Question 1.
An atom as a whole is electrically neutral
Answer:
True.

Question 2.
The mass of an atom is distributed evenly within it.
Answer:
False. (The mass of atom is not distributed evenly, practically all the mass is concentrated in the nucleus.)

Question 3.
The electron has the same mass as that of the proton.
Answer:
False. (The mass of the electron is much less than that of the proton.)

Question 4.
The electron in the K shell has maximum energy.
Answer:
False. (The electrons in the K shell has minimum energy.)

Question 5.
Isotopes have same atomic number but different atomic mass number.
Answer:
True.

Question 6.
Matter is composed of molecules and molecules are made of atoms.
Answer:
True.

Question 7.
In India, total 22 nuclear reactors in eight places are functioning.
Answer:
True.

Question 8.
The number of electrons in a given orbit is given by the formula n
Answer:
False. (The number of electrons in a given orbit is given by the formula 2n2)

Question 9.
Atomic masses are measured in a unit called the dalton (u).
Answer:
True.

Question 10.
The chemical properties of isotopes are different.
Answer:
False. (The chemical properties of isotopes are the same.)

Question 11.
The maximum capacity of the N shell is 18 electrons.
Answer:
False. (The maximum capacity of the N shell is 32 electrons.)

Question 12.
Deuterium is an isotope of hydrogen.
Answer:
True.

Question 13.
Isotopes are used in the treatment of cancer.
Answer:
True.

Question 14.
Atoms of all elements, except normal hydrogen contain neutrons.
Answer:
True.

Question 15.
Electrons moving in different orbits possess the same amount of energy.
Answer:
False. (Electrons moving in different orbits possess different amounts of energy.

Question 16.
Rutherford discovered the neutron.
Answer:
False. (Chadwick discovered the neutron.)

Question 17.
The nth orbit contains at the most 2n² electrons.
Answer:
True.

Question 18.
Electrons have different energies according to their orbits.
Answer:
True.

Question 19.
The capacity of the second orbit is 18 electrons.
Answer:
False. (The capacity of the second orbit is 8 electrons.)

Question 20.
The radioactive isotope Sodium-24 is used in the medical treatment of cancer.
Answer:
False. (The radioactive isotope Sodium-24 is used for detection of cracks in the underground pipes.)

Question 21.
Uranium-235 is used in the production of electricity.
Answer:
True.

Consider the relation between I the items in the first pair and write the correlation for second pair:

Question 1.
K : 2 : M : …………. .
Answer:
18

Question 2.
Carbon : 2, 4 : : Fluorine : …………….. .
Answer:
2, 7

Question 3.
Nitrogen : Valency three : : Fluorine : …………….. .
Answer:
valency one

Question 4.
Atomic radius : pm : Atomic mass : ……………. .
Answer:
u

Question 5.
NaH : Valency of Na : 1 : : MgCl₂ : Valency of Mg …………… .
Answer:
2

Question 6.
\(35 \mathrm{Cl}\) : number of neutrons 18 : : \({ }^{37} \mathrm{Cl}/latex] : …………….. .
Answer:
number of neutrons 20

Question 7.
Protons : Positive : : ……………. : Neutral.
Answer:
Neutrons.

Match the following:

Question 1.

Column I	Column II
1. Thomson	a. Well defined orbits
2. Rutherford	b. Neutron
3. Chadwick	c. Scattering experiment
4. Bohr	d. Electron

Answer:

Column I	Column II
1. Thomson	d. Electron
2. Rutherford	c. Scattering experiment
3. Chadwick	b. Neutron
4. Bohr	a. Well defined orbits

Question 2.

Column I	Column II
1. Atom	a. Treatment of goitre
2. Isotopes of iodine	b. Protons + Neutrons
3. Atomic mass number	c. Different number of neutrons
4. Isotopes	d. Electrically neutral

Answer:

Column I	Column II
1. Atom	d. Electrically neutral
2. Isotopes of iodine	a. Treatment of goitre
3. Atomic mass number	b. Protons + Neutrons
4. Isotopes	c. Different number of neutrons

Question 3.

Column I	Column II
1. Alpha particles	a. Inert element
2. Uranium-235	b. Negatively charged particles
3. Helium	c.   Positively charged particles
4. Isotopes	d.   Krypton – 92, Barium 141
	e.   U-233, Th-232
	f.    12C, 13C, 14C

Answer:

Column I	Column II
1. Alpha particles	c. Positively charged particles
2. Uranium-235	d. Krypton – 92, Barium 141
3. Helium	a. Inert element
4. Isotopes	f.    12C, 13C, 14C

Distinguish between the following:

Question 1.
Proton and Neutron:
Answer:

Proton	Neutron
1. The proton is positively charged particle	1. The neutron does not have any charge.
2. In an atom, the number of protons is always equal to the number of electrons.	2. In general, in an atom, the number of neutrons is not equal to the number of electrons.

Question 2.
Neutron and Electron:
Answer:

Neutron	Electron
1. The neutron is an electrically neutral particle.	1. The electron is a negatively charged particle.
2. Neutrons are present in the nucleus of an atom.	2. Electrons revolve around the nucleus of the atom in specific orbits.

Question 3.
Proton and Electron:
Answer:

Proton	Electron
1. The proton is a positively charged particle	1. The electron is a negatively charged particle.
2 Protons are present in the nucleus of an atom.	2. Electrons revolve around the nucleus of the atom in specific orbits.

Question 4.
Atomic number and Atomic mass number:
Answer:

Atomic number	Atomic mass number
1. The number of electrons or protons in an atom is called the atomic number.	1. The sum of the number of protons and neutrons in the nucleus of an atom is called the atomic mass number.
2 All the isotopes of an element have the same atomic number.	2. Different isotopes of the same element have different mass numbers.
3. The atomic number is represented by the letter Z.	3. The atomic mass number is represented by the letter A.

Answer the following questions in one sentence each:

Question 1.
Name the particles which are present in the nucleus of an atom.
Answer:
Protons and neutrons are present in the nucleus of an atom.

Question 2.
State the relation between the number of protons, the number of neutrons and the atomic mass number (A) of an element.
Answer:
Atomic mass = Number of + Number of number (A) protons (p) neutrons (n)

Question 3.
Chlorine contains 17 protons and 18 neutrons. What is its atomic mass number?
Answer:
The atomic mass number of chlorine is 35.

Question 4.
Carbon contains 6 protons and 6 neutrons. State its atomic number and atomic mass number.
Answer:
The atomic number of carbon is 6 and the atomic mass number is 12.

Question 5.
State one use of isotopes of cobalt.
Answer:
Isotopes of Cobalt-60 are used in the treatment of cancer.

Question 6.
State one use of isotopes of i uranium.
Answer:
Isotopes of uranium are used for production of electrical energy.

Question 7.
Write the electronic configuration of oxygen.
Answer:
Electronic configuration of oxygen is 2, 6.

Question 8.
Write the electronic configuration of chlorine.
Answer:
Electronic configuration of chlorine is 2, 8, 7.

Question 9.
State the number of electrons in the L shell of lithium.
Answer:
There is one electron in the L shell of lithium.

Question 10.
State the number of electrons in the M shell of argon.
Answer:
There are 8 electrons in the M shell of argon.

Question 11.
State the number of electrons in the K shell of helium.
Answer:
There are two electrons in the K shell of helium.

Question 12.
Name isotopes of hydrogen.
Answer:
Hydrogen, Deuterium and Tritium are the isotopes of hydrogen.

Question 13.
Name two isotopes of carbon.
Answer:
[latex]{ }_{6}^{12} \mathrm{C}\) and \({ }_{6}^{14} \mathrm{C}\) are the isotopes of carbon.

Question 14.
Name two elements in which the K and L shells of an atom are completely filled with electrons.
Answer:
The elements are neon and argon.

Question 15.
From the symbol \({ }_{8}^{16} \mathrm{O}\), state the electronic configuration of oxygen and the atomic mass number of isotope oxygen.
Answer:
Electronic configuration of oxygen : 2, 6. Atomic mass number of oxygen : 16.

Question 16.
The atomic mass number of an element is 18, and the element contains 8 electrons. What is the number of protons and neutrons in it?
Answer:
Number of protons : 8, Number of neutrons : 10.

Question 17.
An atom contains 2 protons, 2 electrons and 3 neutrons. State its atomic number and atomic mass number.
Answer:
Atomic number: 2, Atomic mass number: 5.

Question 18.
How many electrons could there be in the outermost orbit of an element whose valency is 3?
Answer:
If the valency of an element is 3 then there is a possibility of 3 or 5 electrons in the outermost orbit.

Question 19.
Which element is used as fuel in atomic reactors?
Answer:
Isotopes of uranium are used as fuel in atomic reactors.

Question 20.
Name the place and the first nuclear reactor in India.
Answer:
Apsara at Bhabha Atomic Research Centre in Mumbai is the first nuclear reactor in India.

Answer the following questions:

Question 1.
Explain Dalton’s atomic theory.
OR
Write the postulates of Dalton’s atomic theory.
Answer:
Dalton’s atomic theory:

1. According to Dalton’s atomic theory matter is made up of atoms and atoms are indivisible and indestructible.
2. All atoms of an element are alike while different element have different atom with different mass.

Try this:

Question a.
Take a solid ball and a Bundi Laddu. Press both these spheres with your palms. What did you find?
Answer:
Solid ball does not break and Bundi Laddu breaks into pieces if you press hard.

Question b.
Cut the solid ball with a sharp knife. What did you find?
Answer:
There is no cavity inside the ball.

Question 2.
How will you think about atomic mass distribution according to Thomson’s I model? Whether this distribution is uniform or non uniform as per Dalton’s atomic theory?
(Use your brainpower!
Answer:
In Thomson’s model the distribution of atomic mass is uniform. Dalton’s atomic theory does not say anything about atomic mass distribution.

Question 3.
If the striker flicked by you misses the coin that you aimed at, where would the striker go?
Can you tell?
Answer:
The striker will continue to move practically with the same velocity till it strikes some other coin or the edge of the board or enter the pocket.

Question 4.
If the striker hits the coin, in which direction would it go? Straight forward to a side or in the reverse direction?
Answer:
Striker may go straight forward or it may be deflected depending upon the exact direction of the motion of the striker.

Question 5.
Draw a neat labelled diagram of Thomson’s atomic model.
Answer:

Question 6.
What were the conclusions drawn from the alpha particle experiment performed hy Rutherford?
Answer:
On the basis of the alpha particle experiment the following conclusions were drawn by Rutherford:

1. An atom has tiny, dense positively charged nucleus at centre of an atom.
2. Most of the mass of the atom is concentrated in the nucleus.
3. Negatively charged particles called electrons revolve around the nucleus.
4. The total negative charge on all the ; electron is equal to the positive charge on ‘ the nucleus. As the opposite charges are balanced, the atom is electrically neutral.
5. There is an empty space between the i revolving electron and the atomic nucleus.

Question 7.
Explain Rutherford’s atomic model.
Answer:

1. An atom has tiny, dense, positively charged core called the nucleus.
   
2. Most of the mass of the atom is concentrated in the nucleus.
3. Electrons bear negative charge. They revolve around the nucleus in orbits.
4. The structure of an atom may be regarded as a miniature of the solar system, the nucleus as the sun and the electrons as the planets.

Question 8.
Which discovery did point out that an atom has internal structure?
(Use your brainpower!
Answer:
The discovery of radioactivity (1896) pointed out that an atom has internal structure.

Question 9.
What is the difference between the solid atom in Dalton’s atomic theory and Thomson’s atomic model?
(Use your brain power!
Answer:
The solid atom in Dalton’s atomic theory is a single particle it does not have any structure and also does not have any constituents. In Thomson’s model, atom is made of positive and negative charges. Thus it is not a single particle. It has constituents and has internal structure.

Question 10.
Explain the difference between the distribution of positive charge in Thomson’s atomic model and Rutherford’s atomic model.
(Use your brain power!
Answer:
According to Thomson’s atomic model, the atom is a homogeneous sphere of positive charge. According to Rutherford’s atomic model, the positive charge is concentrated in the nucleus.

Question 11.
What is the point difference between the place of electron in the atomic models of Thomson and Rutherford?
(Use your brain power!
Answer:
According to Thomson’s atomic model, the negatively charged electrons are embedded in a gel of positive charge and they are stationary. According to Rutherford’s atomic model, the negatively charged electrons revolve around the nucleus.

Question 12.
What is the thing which is present in Rutherford’s atomic model and not present in Dalton’s and Thomson’s atomic models?
(Use your brain power!
Answer:
1. Dalton’s atomic model:
Dalton’s atomic theory does not tell anything about the structure of the atom. There is no mention of electron in Dalton’s atomic theory.

Rutherford’s atomic model:
Rutherford’s atomic model tells about the structure of the atom, i.e. the electron revolving around the nucleus.

2. Thomson’s atomic model:
The electrons are embedded in a gel of positive charge. Here the electrons are stationary and there is no concept of nucleus.

Rutherford’s atomic model:
In Rutherford’s atomic model, the electrons are not stationary, they revolve around the nucleus which is positively charged.

Question 13.
Explain Niels Rohr’s atomic model.
OR
Write the postulates of Bohr’s atomic model.
Answer:
The important postulates of Bohr’s atomic model are as follows:

1. The electrons revolving around the atomic nucleus lie in the concentric circular orbits at certain distance from the nucleus.
2. Energy of an electron is constant while it is in a particular orbit.
3. When an electron jumps from an inner orbit to an outer orbit it absorbs specific amount of energy, and when it jumps from an outer orbit to an inner orbit it emits specific amount of energy.
4. The energy emitted or absorbed during these transitions is equal to energy difference between the initial state and the final state of the electron.

Question 14.
How many types of subatomic particles are found in atom?
Use your brainpower!
Answer:
There are three types of subatomic particles found in atom, viz. the proton, neutron and electron.

Question 15.
Which subatomic particles are electrically charged?
Use your brain power!
Answer:
The proton is a positively charged subatomic particle and the electron is a negatively charged particle.

Question 16.
Which subatomic particles are present in the nucleus?
Use your brain power!
Answer:
The proton and neutron are present in the nucleus.

Question 17.
Where are electrons revolving around the nucleus placed?
Use your brain power!
Answer:
Electrons revolve in the discrete orbits around the nucleus.

Question 18.
State the characteristics of the neutron.
Answer:

1. The neutron is electrically neutral and is denoted by the symbol ‘N’.
2. It is present in the nucleus along with the proton.
3. The mass of the neutron is almost equal to lu which is almost equal to that of the proton.

Question 19.
State the characteristics of protons.
Answer:

1. Protons are positively charged particles and are denoted by the symbol ‘P’.
2. They are present in the nucleus of an atom.
3. The mass of the proton is very nearly equal to lu which is almost equal to that of the hydrogen atom.
4. All the elements contain protons.

Question 20.
State the characteristics of electrons.
Answer:

1. Electrons are negatively charged particles and are denoted by the symbol ‘e’.
2. They have negligible mass.
3. They revolve around the nucleus in certain discrete orbits.
4. In an atom, the number of electrons is equal to the number of protons in its nucleus (Z).

Question 21.
The symbol used for oxygen is ‘O’. There are 8 protons and 8 neutrons in its nucleus. From this determine the 1 atomic number (Z) and mass number (A) of oxygen and arrange these in a 1 conventional symbol.
Use your brain power!
Answer:
Atomic mass number
= Protons + Neutrons
= 8 + 8
Atomic mass number = 16
Atomic number, i.e. the proton number = 8
The conventional symbol = \(\mathrm{A} \mathrm{O}\)
Z = Atomic number
i.e. number of protons is 8.
A = Atomic mass number = 16.
The conventional symbol = \({ }_{8}^{16} \mathrm{O}\).

Question 22.
Atomic number of carbon is 6. How many electrons are there in a carbon atom?
Use your brainpower!
Answer:
The atomic number of carbon, i.e. the proton number of carbon is 6.
The number of electron in the extranuclear part is equal to the number of protons in the nucleus.
∴ The number of electrons in a carbon atom = 6.

Question 23.
A sodium atom contains 11 electrons. What is the atomic number of sodium?
Use your brain power!
Answer:
The number of electron in the extranuclear part is equal to the number of protons, i.e. atomic number. The atomic number of sodium is 11.

Question 24.
The atomic number and mass number of magnesium are 12 and 24 respectively. How will you show this by the convention symbol?
Use your brainpower!
Answer:
The atomic number, atomic mass number and the symbol of an element are written as:

\({ }_{12}^{24} \mathrm{Mg}\) the conventional symbol for magnesium.

Question 25.
The atomic number and mass number of calcium are 20 and 40 respectively. Deduce the number of neutron present in the calcium nucleus.
Use your brain power!
Answer:
There are 20 neutrons in the nucleus of calcium.
[Note: The number of neutrons N = A – Z = 40 – 20 = 20]

Question 26.
Write a note on distribution of electrons in orbits.
OR
What is the maximum number of ( electrons that can be accommodated in each of the orbits (shells) K, L, M, N, etc.?
Answer:
The number of maximum electrons in different orbits of the atom are fixed. The orbit (shell) closest to the nucleus is: given the number 1, the next orbit the ; number 2… etc. The orbits one are designated ; by letters K, L, M, N,… corresponding to the shell numbers n = 1, 2, 3, 4, … etc. The maximum number of electrons in a given orbit is 2n², when n is the number of orbit (shell), thus the first shell has the capacity of 2 electrons, the second 8, the third 18, the fourth 32 and so on. The electrons in the K shell have minimum energy. The electrons in the subsequent shells possess higher energy.

Question 27
There is a similarity in atomic structure and solar system. The planets revolve around the sun due to the gravitational force. Which force might be acting in the atomic structure?
Can you tell?
Answer:
The electric force might be acting in the atomic structure. In the atomic structure, electric force is much stronger than gravitational force.
[Note: Here the gravitational force is very very small compared to the electric force, therefore, the gravitational force can be ignored.]

Question 28.
Positively charged proton are together in the nucleus. What might be, one of the function of the neutrons in the nucleus?
Can you tell?
Answer:
One of the function of the neutrons in the nucleus is to keep the protons and neutrons together by nuclear force.

Question 29.
What do you understand by electronic configuration?
Answer:
The shellwise distribution of the electron in an atom of an element is called the electronic configuration.?

Question 30.
Write the electronic configuration of the following elements:
(1) Hydrogen, (2) Magnesium. (3) Aluminium, (4) Phosphorus, (5) Sulphur.
Answer:

Question 31.
Use the following molecular formulae to determine the valencies of H, Cl, O, S, N, C, Br, I, Na.
Molecular formulae – H₂, HCl, H₂O, H₂S, NH₃, CH₄, HBr, HI, NaH.
Can you recall?
Answer:

Question 32.
Draw suitable diagrams to show the electronic configuration of the atoms of the following elements: Hydrogen, helium, carbon, neon, sodium, chlorine.
Answer:

Question 33.
What are the symbols used for the shells which accommodate the electrons in various atoms?
Use your brain power!
Answer:
The symbols used for the shells which accommodate the electrons are K, L, M, N, … respectively.

Question 34
What is the symbol and ordinal number of the innermost shell?
(Use your brain power!
Answer:
The symbol of the innermost shell is K and ordinal number of the innermost shell is 1.

Question 35.
Write symbol of electron distribution in shell of fluorine atom?
Use your brain power!
Answer:
Symbol for fluorine atom = F,
Electronic configuration of fluorine \(\begin{array}{l}\mathrm{K} \\2\end{array}\), \(\begin{array}{l}\mathrm{L} \\7\end{array}\).

Question 36.
Which is the outermost shell of fluorine atom?
Use your brain power!
Answer:
The outermost shell of fluorine atom is L.

Question 37.
Which is the outermost shell of sodium atom?
Use your brain power!
Answer:
The outermost shell of sodium atom is M shell.

Question 38.
Which is the outermost shell of hydrogen atom?
Use your brain power!
Answer:
The outermost shell of hydrogen is K shell.

Question 39.
What is meant by the atomic number (Z) of an element?
(Use your brain power!
Answer:
Atomic number (Z): The number of electrons or protons in an atom is called the atomic number. It is denoted by Z.

Question 40.
Atomic numbers (Z) of some elements are given here. Write down the number of electron present in the outermost shell of each of them.
Use your brain power!
Answer:

Question 41.
The number of electrons of some elements is given here. By using it write the electronic configuration, number of valence electron and valency of the respective elements.
Use your brain power!
Answer:

Question 42.
Why are the atomic numbers and atomic mass numbers always in whole numbers?
Use your brain power!
Answer:
The total number of protons and neutrons in the nucleus of the atom is called the atomic mass number (A). The number of electrons or protons in an atom is called the atomic number (Z). Both protons and neutrons are whole numbers, therefore, atomic numbers and atomic mass numbers are always in whole numbers.

Question 43.
Sulphur contains 16 protons and 16 neutrons. What would be its atomic number and mass number?
Use your brain power.
Answer:
The atomic number of sulphur is 16 and the atomic mass number is 32.

Question 44.
State the uses of isotopes.
Answer:
Isotopes of some elements are radioactive. Isotopes are used in various fields such as industry, agriculture, medicine, research field.

1. Isotopes of uranium is used for nuclear fission and production of electricity.
2. Cobalt – 60 are used in the treatment of cancer.
3. Iodine – 131 is used in the treatment of goitre.
4. The radioactive isotopes, Sodium – 24 are used for detection of cracks (leakage) in the underground pipes.
5. Radioactive isotopes are used for food preservation from microbes.
6. The radioactive C – 14 is used for determining the age of archaeological objects.

Question 45.
Write a note on nuclear reactor.
Answer:
1. A machine that generates electricity on large scale by using atomic energy is called a nuclear reactor. In a nuclear reactor, the nuclear energy in atom is released by bringing about nuclear reactions on the nuclear fuel.

2. When uranium – 235 is bombarded with a slow speed neutron, it undergoes nuclear fission. Various elements are produced. For example: Krypton – 92 and Barium – 141 along with 2 to 3 neutrons are emitted on fission, these neutron have high speed. Their speed is reduced and they are used for bombarding more Uranium – 235 nuclei.

The process is repeated many times. In this way a chain reaction of nuclear fission takes place (See the figure). A large amount of nuclear energy is released during a chain reaction of fission. The chain reaction is controlled to prevent the probable explosion.

Neutrons are slowed down using graphite or heavy water as moderator. The chain reaction is controlled by absorbing neutron with the help of rods of boron, cadmium and beryllium. The heat produced in the fission is taken out by water as coolent. Water is converted into steam. The available heat is used to drive turbines to produce electricity.

Give scientific reasons:

Question 1.
In Rutherford’s experiment, some alpha particles colliding with the thin gold foil are turned back.
Answer:
1. All the positive charges in an atom is concentrated in a very small region at the centre of the atom. This region is called the nucleus. Electrons revolve around the nucleus, but most of the atom is empty. Alpha particles are positively charged.

2. When a thin sheet of gold is bombarded by alpha particles, most of the particles pass through it without deviation as the atom is almost empty. But some alpha particles move directly towards the positive nuclei, collide with them and due to the electric repulsion, turn back. Thus, in Rutherford’s experiment, some alpha particles colliding with the thin gold foil are turned back.

Question 2.
Two electrons in helium atom are placed in only one shell while three electrons in lithium atom occupy two shells.
Answer:
1. The electronic configuration of helium is (2). It indicates that helium atom has two electrons. Both the electrons are accommodated in the K shell. The maximum capacity of the K shell is two electrons and is maintained in all the elements. Hence, two electrons in helium are placed in only one shell.

2. The electronic configuration of lithium is (2, 1). It indicates that lithium atom has three electrons. The first shell K accommodates two electrons, i.e., the maximum capacity of the K shell. The remaining electron is accommodated in the next shell, i.e., the L shell. Thus, three electrons in lithium occupy two shells (K and L).

Complete the following:

Question 1.
Complete the table by putting tick mark in appropriate box.
Answer:
Types of substances:

Question 2.
Complete the table:
Answer:

Write the maximum number of electron in a shell using the above table. K Shell : 2, L Shell : 8, M Shell : 18, N Shell : 32.

Question 3.
Complete the table:
Answer:
Electronic configuration of some elements:

Question 4.
Complete the following table:
Answer:
Relationship between valency and electronic configuration:

Question 5.
In table 4 column you have written of that element? How many electrons identified valency from its molecular are used to complete the octet? formulae. When the number of the valency electrons in an element ‘x’ is 4 or less than 4, does ‘x’ match with the valency of that element?
Use your brain power!
Answer:
When the number of the valence electrons in an element x is 4 or less than 4, then x matches with the valency of that element.

Question 6.
When the number of the valence electrons in an element ‘x’ is 4 or more than 4, does’(8 – x)’ match with the valency of that element? How many electrons are used to complete the octet?
(Use your brain power!
Answer:
When the number of the valence electrons in an element x is 4 or more than 4, then (8-x) matches with the valency of that element. (8-x) electrons are used to complete the octet.

Question 7
Complete the table:
Answer:

Isotopes	Proton number	Neutron number
\({ }_{1}^{1} \mathrm{H}\)	1	–
\({ }_{1}^{2} \mathrm{H}\)	1	1
\({ }_{17}^{35} \mathrm{Cl}\)	1	2
\({ }_{17}^{35} \mathrm{Cl}\)	17	18
\({ }_{17}^{37} \mathrm{Cl}\)	17	20

 

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 4 Current Electricity and Magnetism Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 8 Science Solutions Chapter 4 Current Electricity and Magnetism

Class 8 Science Chapter 4 Current Electricity and Magnetism Textbook Questions and Answers

1. Write proper words from the following group of words in the blanks and rewrite the completed sentences:
(magnetism, 4.5V, 3.0V, gravitational attraction, potential difference, potential, higher, lower, 0V)

Question a.
Water in the waterfall flows from a higher level to the lower level because of …………… .
Answer:
Water in the waterfall flows from a higher level to the lower level because of gravitational attraction.

Question b.
In an electric circuit, electrons flow from a point of potential to the point of ……….. potential.
Answer:
In an electric circuit, electrons flow from a point of lower potential to the point of higher potential.

Question c.
The difference between the electrostatic potential of the positive end and the negative end of an electric cell is the …………. of the cell.
Answer:
The difference between the electrostatic potential of the positive end and the negative end of an electric cell is the potential difference of the cell.

Question d.
Three electric cells of potential difference 1.5 V each have been connected as a battery. The potential difference of the battery will be ……………… V.
Answer:
Three electric cells of potential difference 1.5 V each have been connected as a battery. The potential difference of the battery will be 4.5 V.

Question e.
An electric current flowing in a wire creates ………………… around the wire.
Answer:
An electric current flowing in a wire creates magnetism around the wire.

2. A battery is to be formed by joining 3 dry cells with connecting wires. Show how you will connect the wires by drawing a diagram.

Question a.
A battery is to be formed by joining 3 dry cells with connecting wires. Show how you will connect the wires by drawing a diagram.
Answer:

3. In an electric circuit, a battery and a bulb have been connected and the battery consists of two cells of equal potential difference. If the bulb is not glowing, then which tests will you perform in order to find out the reason for the bulb not glowing?

Question a.
In an electric circuit, a battery and a bulb have been connected and the battery consists of two cells of equal potential difference. If the bulb is not glowing, then which tests will you perform in order to find out the reason for the bulb not glowing?
Answer:
If you can see the filament of the bulb, check whether it is intact or broken. Check whether the cells are connected in a proper manner:

Or in a wrong way:
If they are connected in a wrong way as shown above, the total potential difference will be 2V + (-2V) = zero.
Figures for reference:

4. Electric cells having potential difference 2V each have been connected in the form of a battery. What will be the total potential difference of the battery in both cases?

Question a.
Electric cells having potential difference 2V each have been connected in the form of a battery. What will be the total potential difference of the battery in both cases?

Answer:
(i) 6V
(ii) 8V.
[Note: In (i), three cells are connected in series.
∴ Total potential difference = 2V + 2V + 2V = 6V.
In (ii), four cells are connected in series.
∴ Total potential difference = 2V + 2V + 2V + 2V
= 8 V]

5. Describe the construction, working and usefulness of a dry cell, with the help of a diagram.
Question a.
Describe the construction, working and usefulness of a dry cell, with the help of a diagram.
Answer:

Dry cell:
Take a lead dry cell and remove its outer coating. Inside you will find a whitish, metal layer. This is the zinc (Zn) metal layer. This is the negative terminal of the cell. Now, carefully break open this layer. There is another layer inside. An electrolyte is filled between these two layers.

The electrolyte contains negatively charged and positively charged ions. These are the carriers of electricity. The electrolyte is a wet pulp of zinc chloride (ZnCl₂) and ammonium chloride (NH₄Cl). There is a graphite rod at the centre of the cell. This is positive terminal of the cell. A paste of manganese dioxide (MnO₂) is filled outside the rod. Because of the chemical reactions of all these chemicals, electrical charge is produced on the two terminals (graphite rod and zinc layer) and an electric current flows in the circuit.

Due to the wet pulp used in this cell, the chemical reaction proceeds very slowly. Hence a large electric current cannot be obtained from this. Compared to the electric cells using liquids, the shelf life of dry cells is longer. Dry cells are very convenient to use as these can be held in any direction with respect to ground and can be used in mobile instruments such as radio sets, wall clocks and torches.

6. Describe the construction and working of an electric bell with the help of a diagram.

Question a.
Describe the construction and working of an electric bell with the help of a diagram.
Answer:
Figure shows the construction of an electric bell and also the electric circuit. The bell consists of an electromagnet, contact screw, iron strip, metal striker and metal gong. A coil of copper wire wound around an iron piece works as an electromagnet and an iron strip along with a striker is fitted near it. A contact screw touches the strip.

The circuit is closed with the key. The current flows in the circuit when the screw is in contact with the iron strip. The current – carrying coil becomes a magnet and attracts the iron strip towards it. As a result, the metal striker hits the metal gong producing sound. At the same time, the screw loses the contact with the strip. The circuit is now incomplete.

Hence, no current flows in the circuit. Therefore, the electromagnet loses its magnetism and the electric iron strip returns to its initial condition, making contact with the screw. As the circuit is now completed, the electromagnet attracts the iron strip and the striker strikes the gong producing sound.

The action repeats itself and the bell continues to ring till the circuit is broken by opening the key in the circuit.
The working of the electric bell is thus based on the magnetic effect of electric current.

Project:

Present all the activities that you performed in this chapter in Science exhibition.

Class 8 Science Chapter 4 Current Electricity and Magnetism Additional Important Questions and Answers

Rewrite the sentences after filling the blanks:

Question 1.
The SI unit of electric charge is the ……………… .
Answer:
The SI unit of electric charge is the coulomb.

Question 2.
The SI unit of electric current is the ……………… .
Answer:
The SI unit of electric current is the ampere.

Question 3.
The SI unit of electric potential is the ………………. .
Answer:
The SI unit of electric potential is the volt.

Question 4.
1 ampere = 1 coulomb per …………… .
Answer:
1 ampere = 1 coulomb per second.

Question 5.
When a glass rod is rubbed on a silk cloth, the glass rod acquires …………… charge.
Answer:
When a glass rod is rubbed on a silk cloth, the glass rod acquires positive charge.

Rewrite the following statements selecting the correct options:

Question 1.
The potential difference between the two electrodes of the lead-acid cell is nearly ………………. .
(a) 1 V
(b) 1.2 V
(c) 1.5 V
(d) 2 V
Answer:
(d) 2 V

Question 2.
The Ni-Cd cell delivers a potential difference of …………….. .
(a) 1 V
(b) 1.2 V
(c) 1.5 V
(d) 2 V
Answer:
(b) 1.2 V

Question 3.
…………….. is a scalar quantity.
(a) Force
(b) Acceleration
(c) Velocity
(d) Electric current
Answer:
(d) Electric current

Question 4.
The working of an electric bell is based on ………….. .
(a) the heating effect of electric current
(b) the chemical effect of electric current
(c) the magnetic effect of electric current
(d) the optical effect of electric current
Answer:
(c) the magnetic effect of electric current

Question 5.
The coulomb is the SI unit of electric ………….. .
(a) current
(b) resistance
(c) potential
(d) charge
Answer:
(d) charge

State whether the following statements are True or False:

Question 1.
The SI unit of electric potential is the ampere.
Answer:
False. (The SI unit of electric potential is the volt. OR The SI unit of electric current is the ampere.)

Question 2.
In the external circuit, the conventional current flows from the positive terminal of the cell to the negative terminal of the cell.
Answer:
True.

Question 3.
Very small current flows when lightning occurs.
Answer:
False. (A large current flows when lightning occurs.)

Question 4.
Sensation is felt by us due to a microscopically small current flowing to the brain.
Answer:
True.

Question 5.
In a car battery, a current is produced by the flow of both negatively and positively charged particles.
Answer:
True.

Identify the odd term:

Question 1.
Pressure exerted by a liquid, Electric current, Electric potential difference, Buoyant force.
Answer:
Buoyant force. It is a vector quantity. Others are scalar quantities.

Question 2.
Electric bulb, Electric heater, Electric bell, Electric iron.
Answer:
Electric bell. Its working is based on the magnetic effect of electric current. The working of other devices is based on the heating effect of electric current.

Answer the following questions in one sentence:

Question 1.
State the relation among the SI units of electric current, electric charge and time.
Answer:
1 ampere = 1 coulomb per second.

Question 2.
Name the positive terminal of the dry cell.
Answer:
The graphite rod at the centre is the positive terminal of the dry cell.

Question 3.
What constitutes an electric current in a metal?
Answer:
A continuous flow of electrons constitutes an electric current in a metal.

Question 4.
What is a battery?
Answer:
A group of two or more cells connected in series to obtain more potential difference is called a battery.

Question 5.
What is a solar cell?
Answer:
A solar cell is a device that converts solar energy into electrical energy.

Question 6.
State one characteristic of the Ni-Cd cell.
Answer:
The Ni-Cd cell is rechargeable.

Question 7.
Give one example in which the magnetic effect of electric current is used.
Answer:
The working of an electric bell is based on the magnetic effect of electric current.

Answer the following questions:

Question 1.
When do we get current electricity?
Answer:
We get current electricity when charged particles such as electrons, positive ions and negative ions are made to flow in a conductor by applying electric force.

Question 2.
Explain the concept of electrostatic potential (electric potential).
Answer:
A liquid flows from a higher level to a lower level. Heat flows from a body at a higher temperature to a body at a lower temperature. Also when different parts of a body are at different temperatures, heat flows from the part at a higher temperature to the part at a lower temperature.

Similarly, a positive charge (free to move) flows from a point at a higher electric level to a point at a lower electric level and a negative charge (free to move) flows from a point at a lower electric level to a point at a higher electric level. The electric level deciding the direction of flow of electric charge is called electrostatic potential (electric potential).

Question 3.
What is the SI unit of electric potential?
Answer:
The SI unit of electric potential is the volt (V).
[Note : This unit is named in honour of Alessandro Volta (1745-1827), Italian physicist, the inventor of the electric battery.]

Question 4.
What is potential difference?
Answer:
Potential difference is the difference
between the potentials at two points. It is similar to the height of a waterfall or the temperature difference between a hot body and a cold body. Potential difference is expressed in volt.

Try this: 

Take connecting copper wires and connect the ‘circuit’ as shown in Fig.(a). No current is seen to flow in the bulb. Now connect in the same ‘circuit’ a 1.5 V dry cell available in the market as shown in Fig.(b). Now it will be realized from glowing of the bulb that a current is flowing in the circuit. Electrons in the wire flow due to the potential difference between the two ends

In Fig.(a), there is no current as ) there is no potential difference in the absence of any cell. Current starts flowing in the circuit as soon as the potential difference is applied. The unit of potential difference in SI system is the volt (V). We will learn about it in the next standard.

Question 5.
What is electric circuit or electrical circuit?
Answer:
A continuous path consisting of conducting wires, a switch or a plug key and other resistances (for example, resistance of an electric bulb) between the terminals of a cell (or a battery) along which an electric current flows is called an electric circuit.

Question 6.
What is electric current?
Answer:
Electric current is the electric charge flowing through a conductor, such as a metal wire, per unit time.

Question 7.
What is one ampere?
Answer:
If one coulomb of charge is passing through any cross section of a conductor in one second, the amount of current flowing through it is called one ampere.
[Note: 1 ampere = 1 coulomb per second OR 1A = 1 C/s. The coulomb is named in honour of Charles Augustin de Coulomb (1736 – 1806), French physicist. The ampere is named in honour of Andre Ampere (1175 – 1836), French physicist and mathematician.]

Think about it:

Question a.
How can we measure water flow emerging from a pipe? We can find it from the amount of water (litres) coming out in a specific time period. How then is the electric current measured?
Answer:
Electric current, I = Q/t. In principle, if we can measure the quantity of charge (Q) flowing through a cross section of a conductor in time t, we can determine the current (i) using this formula (for a steady current). In practice, this is not done. Usually, electric current is measured using the magnetic effect of electric current. One can also use the heating effect and chemical effect of electric current for measurement of electric current.

Question 8.
What is an electric cell? What is its main function?
Answer:
An electric cell is a general device used to produce a uniform flow of charges in a circuit. Its main function is to maintain a constant potential difference between its two terminals.

Question 9.
Name ten devices in which electric cells are used.
Answer:
Electric cells are used in radio sets, wall clocks, wrist watches, torches, toys, mobile phones, cars, invertors, remote controls, ships, submarines, satellites, etc.

Question 10.
Draw a neat labelled diagram to show the design of the lead-acid cell and explain its principle of working.
Answer:
The lead-acid cell contains two electrodes, Pb and PbO₂, dipped in dilute H₂SO₄. Chemical reaction between the substances in the cell produces electric charges on the electrodes. PbO₂ carries a positive charge and Pb carries a negative charge. The potential difference between the electrodes is nearly 2V.

If a load, such as a bulb, is connected externally between the two electrodes, an electric current flows through it. It can deliver a large current. This cell can be recharged after getting electrically discharged.

Question 11.
State applications of the lead-acid cell.
Answer:
Lead-acid cells are connected in series to obtain higher potential difference. The lead-acid battery is used in cars, trucks, motorcycles and uninterrupted power supplies (UPS).

Question 12.
What is the potential difference delivered by the Ni-Cd cell?
Answer:
The potential difference delivered by the Ni-Cd cell is (about) 1.2 V.
[Note: In this cell, nickel oxide is the positive electrode and cadmium is the negative electrode. It is often used as a dry cell and it can be recharged. These cells are used in some portable machines that run on electricity like a drilling machine or a gardening tool.]

Question 13.
Draw a neat labelled diagram of a simple electric circuit containing a cell, an electric bulb and a plug key. What happens when the key is (i) open (ii) closed?
Answer:

(i) When the key is open, there is no current in the circuit. Hence, the bulb does not glow.
(ii) When the key is closed, a current flows in the circuit. Hence, the bulb glows.

Figure for reference:
Here, six cells can be connected in series to obtain more potential difference.

Research:
Lithium ion cells are used in modern equipment for example, a smart phone, laptop, etc. These cells can be recharged. More electrical energy can be stored in these cells as compared to that in Ni-Cd cells.

Question 14.
See Fig. What is the potential difference between A and B if each cell delivers a potential difference of 2V?

Answer:
Potential difference between A and B
= 2V + 2V + (-2V) + 2V = 4V.

Use your brain power!

Question a.
You must have seen the car battery available in the market. It is called a battery and not a cell. Why?
Answer:
In a car battery, a number of cells are connected in series to obtain more potential difference.

Here, two identical cells are connected in parallel. The potential difference between A and B is 2V. This arrangement can be used for a longer time compared to a single cell.

Series and parallel arrangement for higher potential difference and longer life.
Here, the potential difference between A and B is 8V.

Try this:

Magnetic effects of electric current :
Activity 1 :
Take the inside tray of a used up matchbox. Place a small magnetic needle inside the tray. Now take a long connecting wire and wind it around the tray. Complete the electric circuit by connecting in it, this wire, electric cell, plug key and a bulb Figure.

Mark the position of the magnetic needle. Take a bar magnet near to the magnetic needle.
1. What do you observe? Keep looking at the needle and close the plug key. The bulb will light up, and you will realize that the current has started flowing.
2. Does the magnetic needle change its position? Now open the plug key.
3. Does the magnetic needle come back to the original position?
4. What will you conclude from this experiment?
You know that a magnetic needle is indeed a magnet. You have seen that the magnetic needle changes its direction when a bar magnet is taken near the magnetic needle. Also, you have observed that the magnetic needle changes its direction when a current starts flowing in the circuit. This means that magnetic field is created when an electric current flows in a wire. Hans Christian Oersted made this observation first. Briefly we can say that when an electric current passes through a wire, a magnetic field is produced around that wire.
Answer:

1. The magnetic needle is deflected.
2. Yes.
3. Yes.
4. The electric current produces a magnetic field around a current-carrying conductor.

Activity 2 :
Take a metre long flexible copper wire having resistive coating and wind it tightly on a long iron screw. Connect the two ends of the wire in a circuit as shown in the Figure. Also connect an electric cell and a plug key in the circuit. Keep 2-4 iron pins/small nails near the screw. Now start the current in the circuit by plugging the key. It will be noticed that the pins/nails have stuck to the tip of the screw. Will the pins/nails continue to stick when the plug key is opened?

Answer:
No.
When the electric current flows in the wire, magnetism is produced in the coil around the screw and because of that the screw also attains magnetism. As soon as the current is stopped, this magnetism vanishes. The system of the coil and the screw is called an electromagnet. You have seen various uses of the electromagnet in the sixth standard. Electromagnets are used to produce a strong magnetic field useful in scientific research.

Question 15.
What is an electromagnet? State ! its applications.
Answer:
If a coil is wound around an iron screw (or an iron rod) and a current is passed through the coil with a cell (or a battery), the screw behaves as a magnet as long as there is current in the coil. The i system of the coil and the screw is called an electromagnet. It is an example of magnetic effect of electric current.
Applications: Electric bell, cranes for moving heavy loads from one place to another, toys that run on electric cells.

Question 16.
How can the strength of an electromagnet be increased?
Answer:
The strength of an electromagnet can be increased by increasing the current producing the magnetic field.

Question 17.
What is the use of the elastic iron strip in the electric bell?
Answer:
Due to the elastic iron strip, the making and breaking of the circuit occur alternately and the bell continues to ring as long as the key in the circuit is closed.

Question 18.
What will happen if the elastic iron strip in the electric bell loses its flexibility?
Answer:
When the circuit breaks and the electromagnet loses its magnetism, the strip, due to loss of flexibility, will not return to its normal position of contact with the screw. Hence, the circuit will not be completed and the bell will not ring.

Balbharti Maharashtra State Board Class 7 Geography Solutions Chapter 5 Winds Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Geography Solutions Chapter 5 Winds

Class 7 Geography Chapter 5 Winds Textbook Questions and Answers

1. Rewrite the following statements after choosing the correct option:

Question 1.
When the air expands, it ______.
(a) becomes solid,
(b) becomes thinner,
(c) gets lost.
(d) becomes humid.
Answer:
(b) becomes thinner,

Question 2.
From high air pressure regions, winds ______.
(a) blow to regions of still higher pressure.
(b) blow towards regions of cooler air.
(c) blow towards regions of low air pressure.
(d) remains still.
Answer:
(c) blow towards regions of low air pressure.

Question 3.
In the northern hemisphere, winds blowing towards the equator due to the _____.
rotation of the earth.
(a) turn to the south
(b) turn to the east,
(c) turn to the west
(d) turn to the north.
Answer:
(c) turn to the west

Question 4.
The direction of seasonal winds blowing over the Indian subcontinent during winter is from the _____.
(a) south-east to north-west.
(b) south-west towards north-east.
(c) north-east to south-west.
(d) north-west to south-east.
Answer:
(c) north-east to south-west.

Question 5.
The Roaring Forties in the southern hemisphere ______.
(a) blow towards the equator.
(b) blow in the areas around 40°S parallel.
(c) blow from the subpolar region of low pressure.
Answer:
(b) blow in the areas around 40°S parallel.

2. Identify the type of winds from the description given below:

Question 1.
These winds from the south-west bring rains to Indian subcontinent. During June to September, India gets rains. After this period these winds retreat.
Answer:
South West Monsoon Winds.

Question 2.
These winds blowing from the north pole region towards 60°N parallel cause cold wave conditions in extensive areas covering North America, Europe and Russia
Answer:
Polar Winds.

Question 3.
Hilltops get heated quickly during the day. The air in this part becomes hot, light and starts ascending. Hence, a low pressure area forms in this region. At the same time the air at the foothills become cooler and also experiences high pressure. Air in that area blows towards low pressure.
Answer:
Valley Winds.

3. Given below are the values of air pressure in millibars. Using the same, draw diagrams to show a cyclone and an anticyclone:

Question 1.
990, 994, 996,1000
Answer:

Question 2.
1030,1020,1010,1000
Answer:

4. State one reason why:

Question 1.
A belt of calm exists near the equator.
Answer:
(i) A belt of calm exists near the equator because there is not much difference in the temperature and air pressure.
(ii) So winds do not blow in this region.

Question 2.
The winds coming from the north-west in the southern hemisphere have greater velocities than the winds coming from the south-west in the northern hemisphere.
Answer:
(i) In the southern hemisphere the obstacle caused by the relief of the land surface is almost absent.
(ii) Therefore the winds coming from the north – west in the southern hemisphere have greater velocity than the winds coming from the south-west in the northern hemisphere.

Question 3.
The monsoon winds in the summer come from the sea but the retreating monsoon winds come from land.
Answer:
(i) Monsoon winds are generated due to the uneven heating of land and water in the different seasons.

(ii) During summers, land heats up quickly as compared to water & an area of low pressure is created on the land whereas an area of high pressure is created on the water.

(iii) But during winters low pressure is created on the water and an area of high pressure is created on land as it cools down quickly as compared to the water.

(iv) As winds blow from high pressure areas to low pressure areas, it blows from sea to land in summers & from land to sea in winters.
Thus the monsoon winds in summer come from sea but the retreating monsoon winds come from land.

5. Complete the flow chart:

Answer:

6. Answer in short:

Question 1.
Why is the air pressure high in polar areas in both the hemispheres?
Answer:

• In both the polar areas the temperature here is below 0°C.
• Hence the air is cold & heavy.
• Hence the air pressure is high in the polar areas in both the hemispheres.

Question 2.
What effect does the rotation of the earth have on the wind?
Answer:

• The direction of the winds is influenced by the rotation of the earth.
• In the northern hemisphere, winds get deflected towards the right of their original direction, whereas in the southern hemisphere they get deflected toward the left of their original direction.

Question 3.
Why do the cyclonic winds blow in a circular manner?
Answer:
(i) Cyclones are created when a low pressure area is surrounded by high pressure areas. In these conditions, winds start blowing towards the low pressure area from the surrounding high pressure areas.

(ii) But due to the rotation of the earth in the northern hemisphere the winds deflected towards the right of their original direction whereas in the southern hemisphere they get deflected towards the left of their original direction which causes the cyclone winds to blow in a circular manner.

Question 4.
State the reasons that lead to the formation of cyclones and describe the effects of cyclones.
Answer:
(i) Cyclonic conditions are created when a low pressure area is surrounded by high pressure areas.
(ii) In these conditions, winds start blowing towards the low pressure area from the surrounding high pressure areas.
(iii) The effects of cyclone are as follows.

• The sky is cloudy
• Winds blow with a very high velocity
• It rains heavily
• It may cause loss of life and property in coastal regions.

Activity:

Using the internet, obtain information, photos and maps of the recent cyclone that arrived at India’s eastern coast.
Write the social and economic effects of that cyclone.

ICT Question:

Use the mobile app ‘Windyty’ and try to know the direction of winds and pressure areas in the world.

Class 7 Geography Chapter 5 Winds InText Questions and Answers

Formative Assessment
Can you tell?

Observe the diagrams given below. Answer the questions related to sea and land breeze


Question 1.
Why do the breezes blow from the sea to the land during the day?
Answer:
During the day as land gets heated up faster than water, an area of low pressure is created on land whereas there is a region of comparatively higher pressure on the sea. As a result the breezes blow from the sea to the land during the day.

Question 2.
When do the winds blow from the d to the sea?
Answer:
The winds blow from land to the sea during the night.

Question 3.
Describe the winds shown in fig. (a).
Answer:
It is sea breeze.

Question 4.
Compare fig.(a) and (b) with reference fo temperature conditions, air pressure and
winds.
Answer:
In figure (a) the temperature is higher on land & the pressure is low so winds blow from sea to land. In figure (b) the temperature is low on the land & the pressure is high. Winds blow from land to sea.

Question 5.
Which winds are called sea breezes and which are called land breezes? Why?
Answer:
Winds in (a) are sea breeze because they blow from the sea and (b) are land breeze because they blow from the land.

Question 6.
In which part of India are land and sea breezes experienced?
Answer:
In India, it is experienced near the coastal areas.

Question 7.
Do you experience sea and land breezes in your area?
Answer:
The answer may vary.

Give it a try.

Write the changed directions of the wind in the table below:

Question 1.

Pressure Belts	Northern Hemisphere	Southern Hemisphere
Mid Latitudes	………..	…………..
	…………	…………..
Poles	………………..	…………….

Answer:

Pressure Belts	Northern Hemisphere	Southern Hemisphere
Mid Latitudes	(1) Easterlies blow from northeast to south west	Easterlies blow from south east to northwest
	(2) Westerlies blow from southwest to northeast	Westerlies blow from northwest to southeast
Poles	Polar winds blow from northeast to south west	Polar winds blow from southeast to northwest

Try this:

Question 1.
Observe the pictures given below and describe the valley breeze considering the elevation of land, the heating and cooling properties of land and water, the air pressure, etc.

Answer:
Characteristics of Valley Breeze:

• Valleys are cooler compared to mountain tops during the day.
• Mountains are comparatively warmer.
• Air pressure is greater in the valley.
• Winds blow from valley to the mountain tops.
• Hot and light air from the mountains descend downwards and cool air from valleys ascend upwards.
• Valley breeze are set after the sun rises.

Question 2.
Read the following information carefully and draw a diagram for the mountain breeze accordingly.
Characteristics of the Mountain breeze:

• Mountains cool down quickly at night.
• The valley zone is comparatively warmer.
• Air pressure is greater on the mountains.
• Winds blow from the mountain towards the valley.
• The hot and light air from the valley is pushed upwards and the cool air rushes down into the valley.
• Mountain winds set in after sunset.

Answer:

Try this:

• Fold a piece of paper into two same sized rolls.
• Keep both the paper rolls on one side of a table
• You & your friend should select one roll each.

Question 1.
Without touching the roll of the paper on the table, what can be done to move the paper rolls to the other end of the table?
Answer:
To move the paper rolls to the other end of the table without touching a person can

• Blow the air from his mouth towards the roll of paper
• Use a newspaper a book or a hand fan
• Tilt the table towards the other end.

Question 2.
See who moves the paper roll first to the other end of the table:
Answer:
The object which blows the air with maximum force, moves the paper roll first to the other end of the table.

Question 3.
What could be the reason of the delay in making the rolls reach to the other end of the table?
Answer:
There will be a delay in making the rolls reach the other end of the table if the air is blown with lesser force.

Question 4.
What can we do to move the rolls to the other end of the table with a greater speed?
Answer:
We mostly use the technique/object which will blow air with maximum force to move the rolls to the other end of the table with a greater speed.

Question 5.
Can a bottle filled with water be moved to the other end of the table in this manner? Can we use the same method that you tried for moving paper rolls?
Answer:
A bottle filled with water cannot be moved to the other end of the table in this manner. We cannot use the same methods that we tried for moving paper rolls to move a bottle filled with water as it is heavier in weight, (we can if we tilt the table which was an option.)

Class 7 Geography Chapter 5 Winds Additional Important Questions and Answers

Fill in the blanks choosing the correct option from the bracket:

Question 1.
Air moves from high pressure to low pressure areas in a ______ manner. (vertical, horizontal, parallel)
Answer:
horizontal.

Question 2.
Winds velocity is measured in the units of ________. (knots, metres, seconds)
Answer:
knots.

Question 3.
Wind which cover a large portion of the earth are called _____ wind. (local, polar, planetary)
Answer:
planetary.

Question 4.
Winds blowing between mid latitudinal high pressure belt and the equator are called ______. (westerlies, easterlies, polar)
Answer:
easterlies.

Question 5.
Winds blowing between mid latitudinal high pressure belt and the sub polar low pressure belt are called _______. (easterlies, westerlies, polar)
Answer:
westerlies.

Question 6.
Winds that blow for a short duration of time, over a limited area are called ______. wind. (polar, local, easterlies)
Answer:
local.

Question 7.
Mountain winds blow during ______ .(morning, night, midday)
Answer:
night.

Question 8.
Winds that blow at night in coastal areas are called ________ breeze, (sea, land, valley)
Answer:
land.

Question 9.
Cyclones occurring in the western part of the Pacific ocean are called ______.(hurricane, typhoons)
Answer:
typhoons.

Question 10.
Hot winds blowing in the Thar Desert are called the _______ (simoons, loo, chinook)
Answer:
loo.

Rewrite the following statements after choosing the correct option:

Question 1.
During an anticyclone the sky ______.
(a) is dark.
(b) is cloudy.
(c) is clear.
(d) is white.
Answer:
(c) is clear.

Question 2.
Winds blowing from the polar high pressure to sub polar low pressure belt
(a) blow from west to east.
(b) blow from east to west.
(c) blow from south to north.
(d) blow from north to south.
Answer:
(b) blow from east to west.

Question 3.
The minimum velocity of cyclonic storms is ________.
(a) 50 km per hour
(b) 60 km per hour
(c) 70 km per hour
(d) 80 km per hour.
Answer:
(b) 60 km per hour

Question 4.
Winds which originate in specific regions and blow over a limited area are called _____.
(a) local winds.
(b) seasonal winds
(c) monsoon winds
(d) planetary winds
Answer:
(a) local winds.

Find out the odd man out and give reason for your answer:

Question 1.
Polar winds, Local winds, Easterlies, Westerlies
Answer:
Local winds – Others are names of planetary winds.

Question 2.
Landbreeze, Valley winds, Westerlies, Mountain winds.
Answer:
Westerlies – Others are names of local winds.

Question 3.
Mistral, Bora, Pampero, Foehn
Answer:
Foehn – Others are cold and dry winds.

Question 4.
Loo, Foehn, Mistral, Simoon
Answer:
Mistral – Others are hot and dry winds.

Question 5.
Mistral, Bora, Chinook, Foehn
Answer:
Chinook – Others originate in the Alps Mountain.

Question 6.
Southeast Asia, West Europe, East Africa, North Australia.
Answer:
West Europe – Others receive monsoon rains.

Question 7.
India, Japan, China, Phillippines.
Answer:
India – Others experience typhoons.

Question 8.
Furious Fifties, Screaming Seventies, Screeching Sixties,, Roaring Forties.
Answer:
Screaming Seventies – Others are names of winds in the southern hemisphere.

Place a tick mark (✓) against the correct option:

Question 1.
Towards which direction do the southern hemisphere winds get deflected? .
(a) Towards the left.
(b) Towards the right.
(c) Towards the centre.
Answer:
(a) Towards the left.

Question 2.
What are the winds blowing between polar high pressure belt and subpolar low pressure belt called?
(a) Monsoon winds
(b) Polar winds
(c) Westerlies winds
Answer:
(a) Monsoon winds

Question 3.
Hot and destructive winds blowing in the Sahara
(a) Chinook
(b) Simoom
(c) Loo
Answer:
(b) Simoom

Question 4.
Cold winds around the Mediterranean.
(a) Foehn
(b) Pampero
(c) Mistral
Answer:
(b) Pampero

Question 5.
How is cyclonic condition created?
(a) Low pressure area is surrounded by high pressure.
(b) A high pressure area is surrounded by low pressure.
(c) A low pressure area is surrounded by mid pressure.
Answer:
(c) A low pressure area is surrounded by mid pressure.

Identify the type of winds from the description given below:

Question 1.
In coastal areas, land cools down faster as compared to the sea, the air blows from land to sea.
Answer:
Land Breeze.

Question 2.
In the Indian subcontinent, dry winds blow from the Indian Subcontinent towards the equator.
Answer:
North-East monsoon winds.

Question 3.
The winds blowing over the earth’s surface throughout the year and covering a large portion of the earth.
Answer:
Planetary winds.

Question 4.
The winds that blow for a short duration of time, originate in specific regions & blow over a limited area.
Answer:
Local winds.

Match the pairs correctly:

Question 1.

Name of the Wind	Nature of the Wind
(1) Loo	(a) Hot and dry
(2) Simoom	(b) Cold and dry
(3) Chinook	(c) Hot, dry and destructive
(4) Mistral	(d) Warm and dry

Answer:
1 – a
2 – c
3 – d
4 – b

Define the following terms:

Question 1.
Roaring Forties:
Answer:
Beyond 40°S winds blow with tremendous velocity. These winds are called the Roaring Forties.

Question 2.
Furious Fifties:
Answer:
Around 50°S winds are stormy hence they are called the Furious Fifties.

Question 3.
Screeching Sixties:
Answer:
The stormy winds around 60°S make tremendous noise and hence they are called the Screeching Sixties.

Question 4.
Local Winds:
Answer:
The winds that blow for a short duration of time, originate in specific region and blow over a limited area are called Local Winds.

Question 5.
Doldrums:
Answer:
The region up to 5° North and 5° South of the equator remains calm for most of the year and winds do not blow in this region. It is called the equatorial calm zone or Doldrums.

Question 6.
Horse Latitudes:
Answer:
In the area near the Tropic of Cancer and Tropic of Capricorn, that is between 25° and 35° north and south, there exist a high pressure belt, which is a calm belt. This belt is called as the Horse latitudes.

Question 7.
Typhoons:
Answer:
Storms arising in the months between June and October in the western part of the Pacific Ocean which blow with high velocity winds and heavy rains causing destruction are called Typhoons.

Question 8.
Hurricanes:
Answer:
The cyclones in the Caribbean sea which are destructive in nature are called Hurricanes.

Observe the pictures given below of Seasonal winds and write its characteristics:

Question 1.

Answer:
Characteristics of the Seasonal winds (Monsoon):

• Monsoon winds are generated due to the uneven heating of land and water in the different seasons.
• During summer, monsoon winds blow from the sea to the land and in winter they blow from the land to the sea.
• Southern Asia, East Africa, North Australia are the regions where the pronounced effects of these winds are felt.
• The influence of monsoon winds is seen in the summer and winter seasons in the Indian subcontinent.

change in direction of wind:

Draw a neat labelled diagram:

Question 1.
Planetary winds and pressure belts on the earth
Answer:

Distinguish between the following:

Question 1.
Easterlies and Westerlies:
Answer:

Easterlies	Westerlies
(i) Easterlies blow from mid latitudinal high pressure belt to equatorial low pressure belt in both the hemispheres	(i) Westerlies blow from mid latitudinal high pressure belt to subpolar low pressure belt in both the hemispheres
(ii) In the northern hemisphere, they blow from the northeast to the southwest.	(ii) In the northern hemisphere, they blow from the southwest to the northeast.
(iii) In the southern hemisphere, they blow from the southeast to the northwest.	(iii) In the southern hemisphere, they blow from northwest to the southeast.

Question 2.
Valley breeze and Mountain breeze:
Answer:

Valley Breeze	Mountain Breeze
(i) Valley breeze blow during the day.	(i) Mountain breeze blow during the night.
(ii) Winds blow from the valley to the mountain.	(ii) Winds blow from the mountain to the valley.
(iii) Valley breeze blows because of the high pressure area created iin the valley.	(iii) Mountain Breeze blows because of the high pressure area created on the mountains.

Question 3.
Cyclones and Anticyclones:
Answer:

Cyclones	Anticyclones
(i) Cyclonic conditions are created when a low pressure area is surrounded by high pressure areas.	(i) Anticyclonic conditions are created when a high pressure area is surrounded by low pressure areas.
(ii) The cyclonic winds move in an anticlockwise direction in the northern hemisphere and clockwise direction in the southern hemisphere.	(ii) The anticyclonic winds move in a clockwise direction in the northern hemisphere and anticlockwise direction in the southern hemisphere.
(iii) The sky is cloudy.	(iii) The skies are clear.
(iv) The velocity of wind is very high and cause rain.	(iv) The velocity of wind is less and weather is pleasant.

State one reason why:

Question 1.
Planetary winds change their original direction.
Answer:
The rotation from the west to east causes the change in the original direction of the planetary winds.

Question 2.
The air pressure in land and water is different
Answer:
(a) The land is made up of dense matter. Land is stable and opaque. As a result, heat is transferred at a greater speed and in a higher proportion. Hence, land gets heated quickly.

(b) The density of water is comparatively less. Water is transparent and unstable. Hence, water does not get heated quickly.

(c) As a result, the air pressure in land and water areas is different.

Question 3.
The Indian subcontinent experiences monsoon and retreating monsoon seasons.
Answer:
(a) Monsoon winds are generated due to uneven heating of land & water in different seasons. During summers, monsoon winds blow from sea to land & in winter they blow from land to the sea.

(b) The influence of monsoon winds is seen in summer season in the Indian subcontinent due to high temperature & low pressure in Thar desert region & Punjab plains.

(c) As these winds blow from sea to land the Indian subcontinent experiences monsoon (rainy) season.

(d) During winters, due to high pressure & low temperature in the Indian subcontinent & comparatively low pressure & high temperature in the Indian ocean winds blow from land to sea.

(e) This is the retreating monsoon season in the Indian subcontinent.
Thus the Indian subcontinent experiences monsoon & retreating monsoon season.

Answer the following in detail:

Question 1.
Give detailed information about the types of planetary winds.
Answer:
The following are the types of Planetary winds:
(i) Easterlies:

• In both the hemispheres, the winds that blow from the high pressure area between 25° & 35° parallels, to the equatorial low pressure belt (between 5°N & 5°S parallel) are called Easterlies.
• In the northern hemisphere they blow from northeast to southwest whereas in the southern hemisphere they blow from southeast to the northwest.

(ii) Westerlies:

• In both the hemispheres, winds that blow from the mid-latitudinal high pressure belt to sub polar low pressure belt situated near 60° parallel are called westerlies.
• In the northern hemisphere, these winds blow from the southwest to the northeast & in the southern hemisphere, they blow from the northwest to the southeast.

(iii) Polar winds:

• In both the hemispheres, winds blowing from the polar high pressure belt to the sub polar low pressure belt (55° to 65°) are called polar winds.
• Generally they blow from east to west.

Question 2.
Write in detail about cyclonic storms.
Answer:
(i) Cyclones occurring in the western part of the Pacific ocean along the coasts of Japan, China, Philippines, etc. are known as ‘Typhoons’.
(ii) These storms arise in the months between June & October.
(iii) Due to high velocity winds & heavy rains, these prove to be destructive.
(iv) The cyclones in the Caribbean Sea are known as ‘hurricanes’. These are also destructive in nature.
(v) During these storms, the minimum velocity of the wind is 60 km per hour.
(vi) Cyclones also originate in the temperate zone but they are not so powerful & hence are not destructive.

Question 3.
What are anticyclones?
Answer:
(i) Under specific atmospheric conditions, the air pressure in a particular region increases & the pressure in the surrounding areas remain low.

(ii) In this situation, winds blow from the centre towards the surrounding areas in a circular manner.

(iii) In the northern hemisphere, these winds blow in a clockwise direction whereas in the southern hemisphere they blow in an anticlockwise direction.

(iv) During anticyclone, the skies are clear, winds blow with lesser velocities and the weather is pleasant.

Can you tell?

Observe the picture given below and answer the following questions.:

Question 1.
Which are the winds in the northern hemisphere that blow from the mid latitudinal high pressure belt to the equatorial low pressure belt?
Answer:
Easterlies blow from mid latitudinal high pressure belt to equatorial low pressure belt in the northern hemisphere

Question 2.
What is the direction of the Westerlies in the southern hemisphere?
Answer:
Westerlies blow from north west to south east in the southern hemisphere

Question 3.
Which planetary winds blow from the mid-latitudinal high pressure belts to the subpolar low pressure belts in the northern hemisphere?
Answer:
The Westerlies blow from mid latitudinal high pressure belts to subpolar low pressure belts in the northern hemisphere

Question 4.
Why is the direction of polar winds not the same in both the hemispheres?
Answer:
The rotation of the earth causes the change in the direction of winds in both the hemisphere. So polar winds blow from northeast to south west in the northern hemisphere & from south east to north-west in the southern hemisphere.

Question 5.
Name the winds that blow in the southern hemisphere.
Answer:
Easterlies, Westerlies and Polar Winds blow in the southern hemisphere.

Question 6.
In which direction do the Easterlies blow in the Northern and Southern hemisphere?
Answer:
Easterlies blow from northeast to southeast in northern hemisphere & from southeast to northwest in the southern hemisphere.

Balbharti Maharashtra State Board Class 7 Geography Solutions Chapter 9 Agriculture Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 Geography Solutions Chapter 9 Agriculture

Class 7 Geography Chapter 9 Agriculture Textbook Questions and Answers

1. Select the proper option for the following statements:

Question 1.
In which of the following type of farming
are the crops rotated?
(a) Intensive.
(c) Commercial.
(b) Plantation.
(d) All of these.
Answer:
(a) Intensive.

Question 2.
Agriculture requires the following:
(a) Only ploughing
(b) Use of animals, implements, machines and manpower.
(c) Use of only manpower.
(d) Just cultivate the crop.
Answer:
(b) Use of animals, implements, machines and manpower.

Question 3.
In India, agriculture has developed because…
(a) There are two seasons of agriculture in India.
(b) Majority of the people depend on agriculture.
(c) Traditional agriculture is practised in India.
(d) In India factors like climate, soils, water, etc. are conducive.
Answer:
(d) In India factors like climate, soils, water, etc. are conducive.

Question 4.
It is necessary that modern methods and technology be used in agriculture in India because…
(a) There are factories producing improved seeds.
(b) There are industries producing fertilizers
(c) Population is growing and there are agro-based industries.
(d) Modern means and machines are available.
Answer:
(c) Population is growing and there are agro-based industries.

2. Give short answers for the following questions:

Question 1.
Describe the importance of irrigation for agriculture.
Answer:
(i) Irrigation means the process of supplying of water through artificial means such as pipes, canals, sprinklers, etc.
(ii) Irrigation helps the farmers to be less dependent on rain water for the purpose of agriculture.
(iii) Since monsoons are uncertain & highly variable, farming cannot entirely depend upon rains
(iv) Hence irrigation is needed to grow assured crops & also to grow crops in the months after the monsoon season.

Question 2.
Distinguish between intensive farming & shifting cultivation.
Answer:

intensive farming	Shifting Cultivation
(i) Intensive farming is carried out in one and the same farm for years together. (ii) This type of farming is mostly seen in the developing regions. (iii) In this type of farming the cultivator and his family are totally dependent on farming. Farm production is sufficient only for the requirement of the family.	(i) In shifting Cultivation, every year a new area is chosen for cultivation. (ii) This type of cultivation is practised in the tropics in densely forested areas or hilly tracts. (iii) The production obtained from shifting cultivation is not sufficient to fulfill the food requirement. So people undertake hunting, fishing and gathering of bulbs and roots from forest.

Question 3.
Mention the major types of farming and give information about intensive farming and extensive grain farming?
Answer:
Broadly the following types of farming are identified

Intensive farming:

• Intensive farming is a type of traditional farming. It is carried out in one and the same farm for years together.
• Getting maximum production from a minimum area is the characteristic of Intensive farming.
• Due to large population or limited availability of land, per head holding is small.
• This type of farming is mostly seen in developing region.
• The cultivator and his family are totally dependent on farming. The farm production is sufficient only for the requirements of the cultivators family.
• As farm production is low hence the economic condition of the cultivator is also poor.

Extensive farming:

• Extensive grain farming is a type of commercial farming.
• Farm size is greater than 200 hectares.
• Due to large farm size and sparse population in the region, this type of farming is carried out with the help of machines like tractors and crushers.
• Helicopters or planes are used for spraying pesticides.
• Mono crop cultivation is the main characteristic.
• Crops like wheat, corn, barley, oats, soyabean are cultivated.
• Heavy capital investment is necessary. Since huge expenditures are needed for purchase of machinery, fertilisers, pesticides, godowns, transport cost, etc.
• Droughts, attack by pests, locusts, market fluctuation, etc. are the problems in extensive grain farming.
• This type of farming is carried out in the temperate grassland regions.

Question 4.
Describe the characteristics of plantation farming.
Answer:
(i) Plantation farming is a type of commercial farming.
(ii) Farm size is 40 hectares or above.
(iii) As plantation agriculture is practised in hilly tracts of tropical regions, use of machines are not possible hence local manpower is used.
(iv) This is a single crop cultivation practice.
(v) Only commercial crops like tea, rubber, coffee, coconut, cocoa, spices, etc. are planted.
(vi) This type of farming requires large scale capital investment.
(vii) Major issues faced are climate, manpower, deterioration of environment, economic and managerial problems.
(viii) Plantation farming is practised in India and other South Asian countries, Africa, South and Central America.

Question 5.
Which are the crops cultivated in your area? What are the geographical reasons for that?
Answer:
(i) I live in the konkan region of the state of Maharashtra
(ii) The main crops cultivated in our area are mangoes, rice, coconut, cashew, etc.
(iii) Konkan region has hot & humid climate, heavy rainfall which favours the growth of these crops.
(iv) This region has fertile laterite soil which is suitable for cultivation of fruits.

Question 6.
Why is the agriculture in India seasonal in nature? What are the difficulties for perennial agriculture?
Answer:
(i) Most of the agriculture in India is dependent on monsoon rainfall. 80% of the rainfall in India is received from south west monsoon winds from June to September.
(ii) Since monsoon in India is seasonal; agriculture in India is also seasonal in nature.
Difficulties for perennial agriculture
(i) Rainfall in India is highly irregular & uncertain. Also there is lack of irrigation facilities.
(ii) There is lack of capital investment, godowns, transportation, etc.
(iii) There is lack of awareness with respect to scientific methods of crop cultivation.

Activity:

Visit a farm where modern technology is used for agriculture. Collect information about it.

Use of ICT

Question 1.
Collect the pictures of improved seeds and means of irrigation from the internet.
Question 2.
Collect information regarding agricultural in Israel from the internet. and present it.

Class 7 Geography Chapter 9 Agriculture InText Questions and Answers

Can you tell?
Observe the picture and briefly describe the type of agriculture shown.

Question 1.

Answer:
(a) For the growth of fruits a large number of similar trees are grown in a vast area. Such land areas are called farms or orchards, for e.g. mango, coconut.
(b) In this type of farming modern as well as traditional methods are used.
(c) Use of irrigation, chemical fertilizers, green houses, etc. is being made for getting more profit.

Question 2.

Answer:
(a) One single crop is grown in a large area.
(b) The use of man power is less, whereas most of the farmwork is done with the help of machines like tractors, harvesters, threshers, etc.
(c) Heavy capital investment is necessary for this type of farming.

Question 3.

Answer:
(a) One single tree crop is grown on a large scale.
(b) Only commercial crops like tea, rubber, coffee, cocoa, coconut, spices, etc. are planted.
(c) It requires lot of capital investment due to the long duration of crops, use of scientific methods, exportable production, processing,

Question 4.

Answer:
(a) Crops are grown on small farm lands with the help of bovine (animal) and human resources.
(b) The profits earned are very low despite intensive care taken.
(c) The crops that are grown are used for home consumption and the excess, if any, is sold in the local market.

Observe the picture and answer:

Question 1.
What all do you see in the picture?
Answer:
A farmer’s house, a farmer keeps cows, hens, sheep, goats and cattle, a standing crop, a plough share, farmers wife grazing the cattle.

Question 2.
Why has the family kept goats and hens?
Answer:
Farmer gets milk from goats and eggs from the hens.

Question 3.
Which implements are seen in the picture?
Answer:
The spade and plough are seen in the picture

Question 4.
How are these implements used?
Answer:
Spade is a hand tool used to dig or loosen ground or break lumps in the soil. A plough is used for ploughing the fields. Ploughing turns organic matter into soil to increase decomposition and add nutrients from organic matter to the soil.

Question 5.
In which major occupation type will the activities shown here be included?
Answer:
The activities shown in the picture mostly fall under the occupation of agriculture.

Question 6.
What could be the main occupation of these people?
Answer:
The main occupation of these people could be cultivation of crops.

Question 7.
Who could be the owner of the house?
Answer:
The farmer himself could be the owner of the house.

Question 8.
Which products shown in the above picture do you use?
Answer:
Milk and dairy products, eggs are used in our day to day lives.

Give it a try:

Observe the pictures and answer the following questions.

Question 1.
What differences do you observe these pictures?
Answer:
In the pictures we can observe the changes in agricultural practices. It shows the transition from traditional to modern agriculture.
(a) Initially man cultivated crops using only manual labour. Later he started using various animals like bullocks to cultivate crops.
Today we use modern machines for various agricultural practices.

(b) Irrigation too has changed – from water allowed to flow freely in the field though pipes, man now uses modern methods like sprinkler & drip irrigation.

(c) Poultry farming is supplementary to cultivation of crops & is included in agriculture. Initially hens were reared in small numbers in open areas. But today hens are reared on a large scale. With use of modem techniques it leads to large scale production of eggs.

Question 2.
What changes have taken place in traditional agricultural practices?
Answer:
Traditionally agriculture was carried out using manual labour & bovine power. Today modem methods of agriculture include using machines tractors, harvests, fertilizers, insecticides, pesticides, etc. for better yield of crop.

Irrigation is used for ample water supply throughout the year to maximize crop production. Modern, scientific techniques & use of hybrid seed, leads to more productivity of land, (more crop production in limited land area)

Answer the following questions:

Question 1.
Which improper practices arising out of man’s greed are observed in agriculture.
Answer:
In order to produce the fruits and vegetables early and sell them quickly, man uses artificial chemical, which harms the soil & hampers the quality of production.

Question 2.
What means of irrigation are available in your area?
Answer:
(a) Drip and Sprinkler irrigation is used in many orchards across the konkan region of Maharashtra.
(b) Wells & tube wells are other methods used on large scale.

Question 3.
Have you observed the wastage of water in agriculture? If yes, describe it.
Answer:
There was a field in my native place. The farmer would water the field leaving the water pipe on the field. Lot of water would be wasted. But now the same farmer waters the field using sprinkler irrigation method. As a result there is no wastage of water, any more.

Question 4.
Which steps can easily be taken to avoid improper practices in agriculture?
Answer:
(a) System of Agricultural Produce Market committee should be established at taluka level and farmers should be encouraged to bring their produce and sell to the traders here

(b) As farm produce is perishable, there has to be a proper arrangement for its sale to avoid,wastage.

(c) Institutes like farmer’s organizations, consumer societies, etc. help and try to protect farmers from exploitation by agents, mediators and others.

(d) Farmers should not use artificial chemicals and pesticides.

Use your brainpower:

Question 1.
Why does extensive commercial farming need more capital?
Answer:
(a) Farm size is greater than 200 hectares.
(b) Due to large farm size and sparse population in the region, this type of farming is carried out with the help of machines like tractors and crushers.
(c) Pesticides are sprayed with the help of helicopters or planes.
(d) Since huge expenditures are needed for the purchase of machinery, fertilizers, pesticides, godowns, transport cost, etc. So extensive commercial farming needs more capital.

Question 2.
Why does plantation farming need skilled and experienced labour?
Answer:
(a) Farm size in plantation farming is 40 hectares or above.
(b) Plantation farming is practised in hilly tracts, so use of machines is not possible.
Hence, plantation farming needs skilled and experienced labour.

Question 3.
In what different ways is ground water obtained for agriculture?
Answer:
(a) Ground water is the water that is found underground.
(b) When it rains, about 20% of the rain water seeps into the ground, forming a water table.
(c) A well as deep as the water table is dug, in order for it to pump water to the fields for agriculture.
(d) Now days use of tube wells have become popular too

Class 7 Geography Chapter 9 Agriculture Additional Important Questions and Answers

Fill in the blanks choosing the correct options from the bracket:

Question 1.
Commercial dairy fanning is mainly undertaken for _________. (milk and fish, meat and milk, meat and poultry)
Answer:
meat and milk

Question 2.
Sheep rearing is carried out to obtain ________. (cotton, silk, wool)
Answer:
wool

Question 3.
In order to achieve the best growth of fish, ________ methods are employed. (pisciculture, scientific, electronic)
Answer:
scientific

Question 4.
Silk thread is obtained from the ______ of the silk moth. (cocoon, mulberry, skin)
Answer:
cocoon

Question 5.
Leaves of the ______ trees are the main food for the silk worms. (mulberry, pepal, coconut)
Answer:
mulberry

Question 6.
______ farming is a highly specialized type of farming of the modem era. (Intensive, Subsistence, Modern)
Answer:
Greenhouse

Question 7.
Intensive farming and shifting cultivation are the two types in ______ farming. (extensive, traditional, intensive)
Answer:
traditional

Question 8.
Shifting cultivation is a ________ type of cultivation, (primitive, extensive, intensive)
Answer:
primitive

Question 9.
Cultivation of flowers and fruits is a subtype of _______ gardening. (market, organic, plantation)
Answer:
market

Fill in the blanks:

Question 1.
_______ is a new field of tourism.
Answer:
Agrotourism

Question 2.
Most of the farmers are ________ weak and cannot market their product on their own.
Answer:
economically

Question 3.
As farm produce is ______ there has to be a proper arrangement for its sale.
Answer:
perishable

Question 4.
Some of the farm produce is directly used by industries as ______.
Answer:
raw material

Question 5.
_____ is a major exporter of fresh farm produce.
Answer:
Israel

Question 6.
International markets are now becoming easily available for farm produce due to _____.
Answer:
globalization

Question 7.
France and Italy are famous for ________.
Answer:
horticulture

Question 8.
____ is obtained from organic waste.
Answer:
Vermicompost

Select the proper option for the following statements:

Question 1.
Heavy capital investment is necessary for
(a) Subsistence farming
(b) Extensive grain farming
(c) Shifting cultivation
(d) Dairy farming
Answer:
(b) Extensive grain farming

Question 2.
Getting maximum production from a minimum area is the characteristic of
(a) Plantation farming
(b) Intensive farming
(c) Horticulture
(d) Extensive grain farming
Answer:
(b) Intensive farming

Complete the following sentence:

Question 1.
For our basic needs of food and clothing ______.
Answer:
we make use of plants and animals

Question 2.
In agricultural occupation, resources like _______.
Answer:
manpower, animals, implements, etc. are used

Question 3.
In the past primitive man had to wander in the forest to ______.
Answer:
sustain himself on the collected forest produce

Question 4.
Bees in order to collect honey, _______.
Answer:
hover around the plants that bear flowers

Question 5.
Silk thread is obtained from the _________.
Answer:
cocoon of the silk moth

Question 6.
Greenhouse farming facilitates _______.
Answer:
getting maximum product from the land

Question 7.
Greenhouse farming is ________.
Answer:
highly specialized type of farming of the modern era

Question 8.
Different types of agriculture has evolved due to _______.
Answer:
geographical and cultural diversity and technological differences in different regions

Question 9.
Intensive farming is carried out in ________.
Answer:
one and the same farm for years together

Question 10.
In shifting cultivation, ________.
Answer:
every year a new area is chosen for cultivation

Question 11.
The problems in extensive grain farming are ______.
Answer:
droughts, attacks by pests, locusts, etc. and also market fluctuation

Question 12.
Market gardening has developed mainly as a _______.
Answer:
result of urbanization and the ready markets available in urban centres

Question 13.
Cultivation of flowers and fruits is a ________.
Answer:
subtype of market gardening

Question 14.
As farm produce is perishable, _________.
Answer:
there has to be a proper arrangement for its sale

Question 15.
Most of the farmers are ______.
Answer:
economically weak and cannot market their production on their own.

Question 16.
By advertising on the internet, ______.
Answer:
the agricultural products get sold in local as well as international markets

Answer in one sentence:

Question 1.
What do we depend on for our basic needs of food and clothing?
Answer:
For our basic needs of food and clothing, we make use of plants and animals.

Question 2.
What is considered to be the main and the most important occupation in agriculture?
Answer:
In agriculture, cultivation of crops is considered to be the main and the most important occupation.

Question 3.
Why had the primitive man to wander in the forest in the past?
Answer:
Primitive man had to wander in the forest to sustain himself on the collected forest produce.

Question 4.
What is the core of animal husbandry?
Answer:
Rearing different animals and obtaining various products from them for subsistence is the core of animal husbandry.

Question 5.
On what do sheep and goats survive?
Answer:
Sheep and goats survive on short grass, shrubs and acacia, grown in remote hilly areas away from urban settlements.

Question 6.
What do we obtain from Beekeeping occupation?
Answer:
We obtain honey and wax from Beekeeping.

Question 7.
What is Pisciculture?
Answer:
Pisciculture is also called fish farming in which fish seeds are released in the pond to achieve the best growth of fish.

Question 8.
Name the fish reared in fish farms.
Answer:
Warn, Roha, Rawas, Kolambi are reared in fish farms.

Question 9.
What is used to weave soft silk cloth?
Answer:
Fine and strong silk thread obtained from the cocoon of the silk moth are used to weave soft silk cloth.

Question 10.
Which is the highly specialized type of farming of the modem era?
Answer:
Greenhouse farming is a highly specialized type of farming of the modem era.

Question 11.
Which are the two types in traditional farming?
Answer:
Intensive farming and shifting cultivation are the two types in traditional farming.

Question 12.
What is the characteristic of intensive farming?
Answer:
Getting maximum production from a minimum area of land is the characteristic of intensive farming.

Question 13.
Where is shifting cultivation practised?
Answer:
Shifting cultivation is practised in the tropics in densely forested areas or hilly tracts.

Question 14.
Name the two major types of farming covered under commercial farming.
Answer:
Extensive grain farming and plantation agriculture are the two major types of farming covered under commercial farming.

Question 15.
What are the problems in extensive grain farming?
Answer:
The problems in extensive grain farming are droughts, attack by pests, locusts, etc. and market fluctuations.

Question 16.
What are the major issues faced by the plantation farming?
Answer:
Climate, manpower, deterioration of environment, economic and managerial problems are the major issues faced by the plantation farming.

Question 17.
Where is plantation farming practised?
Answer:
Plantation farming is practised in India and other South Asian countries, Africa, South and Central America, etc.

Question 18.
What is a subtype of market gardening?
Answer:
Cultivation of flowers and fruits is a subtype of market gardening.

Question 19.
What are the major products of horticulture?
Answer:
Major products of horticulture are flowers like lily, gerbera, tulip, dahlia, chrysanthemum, marigold, etc.

Question 20.
Name some native and exotic fruits cultivated in fruit farming.
Answer:
Different native and exotic fruits like mangoes, custard apples, grapes, bananas, pomegranates, dragon fruits, cherries, oranges, strawberries, raspberries, etc.

Question 21.
What is organic farming?
Answer:
When farming is done using all vestal matter mixed in the soil, it is called organic farming.

Question 22.
Why do city dwellers visit the rural areas?
Answer:
City dwellers are curious about the farmers life and environment so they visit the rural areas to see the rural life, local customs and culture.

Question 23.
Why are some fruits and vegetables harmful to health?
Answer:
Some fruits and vegetables may have been produced using artificial chemicals, and pesticides for quicker production. Such fruits and vegetables are harmful to health.

Give geographical reasons:

Question 1.
The system of Agricultural Produce Market Committees is established at the Taluka level.
Answer:

• Most of the farmers are economically weak.
• These farmers cannot market their production on their own.
• At these places, farmers bring their produce and sell to the traders.
• Hence, the system of Agricultural produce market committee is established at taluka level.

Question 2.
Poultry occupation is generally located in big cities.
Answer:

• Running a poultry on commercial basis requires a lot of care.
• For this scientific methods are employed.
• Areas in big cities provide a ready market for this occupation.
• Hence poultry occupation is generally located in big cities.

Question 3.
Bee keeping is an important occupation with respect to agriculture.
Answer:

• Beekeeping occupation is undertaken to obtain honey and wax.
• In order to collect honey, bees hover around the plants that bear flowers.
• This promotes the process of pollination .
• Pollination helps the trees to bear large number of fruits and increase the yield of crops. Hence, Bee keeping is an important occupation with respect to agriculture.

Question 4.
Specific type of fish species are reared separately.
Answer:

• During fishing, different types of fish and other aquatic organisms get caught in the fishing nets.
• Separating them becomes a major task.
• All organisms do not fetch the same price. Due to the above factors specific type of fish species are reared separately.

Question 5.
The expenditure of planting mulberry trees every year is saved.
Answer:

• Leaves of mulberry trees are the main food for the silk worms.
• Once planted, the mulberry trees survive for a minimum period of 15 years.
• Hence, the expenditure of planting mulberry trees every year is saved.

Question 6.
Last few years, has seen the development of nurseries.
Answer:

• In the last few years, the area under floriculture cultivation of medicinal and aromatic plants and horticulture has increased.
• These plantations require a high standard of seedlings, cuttings, bulbs and seeds.
• Nurseries give good returns.
• This has led to the development of nurseries.

Question 7.
Heavy capital investment is necessary for extensive grain fanning.
Answer:

• Extensive grain farming Is carried out with the help of machines like tractors and crushers.
• Pesticides are sprayed with the help of helicopters or planes.
• Huge expenditures are needed for the purchase of machinery, fertilizers, pesticides, godowns, transport cost, etc.
• So heavy capital investment is necessary for extensive grain farming.

Question 8.
Market gardening is also known as truck farming.
Answer:

(i) Market gardening has developed as a result of urbanization and the ready markets available in urban centres.

(ii) Farmers cultivate vegetables and other items in the vicinity of urban centres to cater to the demands of city dwellers.

(iii) Market gardening is dependent on good transport network.

(iv) The quality and price of the product is determined by rapid transport. Hence, market gardening is also known as ‘truck farming’.

Question 9.
Agrotourism is financially beneficial for the farmer and his village.
Answer:

• Agrotourism is a new field in tourism.
• In the tropics, various types of agricultural products are cultivated.
• City dwellers are curious about the farmer’s life and environment.
• Many of the city dwellers visit the rural areas to see this. So, Agrotourism is financially beneficial for the farmer and his village.

Question 10.
In intensive farming the economic condition of the cultivator is poor.
Answer:

• Intensive farming is practised in areas of high population.
• Due to large population per head holding is small.
• Because of small land holding & traditional methods of cultivation farm production is sufficient only for the requirement of the family.
• As the farm production is low, the economic conditions of the cultivator is poor.

Question 11.
How do farmers grow their crops?
Answer:

• After deciding what to grow, farmers often till the land by loosening the soil.
• The soil is then mixed with fertilizers.
• Then they sow seeds or plant seedlings.
• When the crops are growing farmer must water the seed and kill crop pests.

Write short notes on:

Question 1.
Greenhouse farming:
Answer:
(i) Greenhouse farming is a highly specialized type of farming of the modem era.

(ii) For erecting a greenhouse galvanized iron pipes and plastic sheets are used. It can have total control on natural factors like climate, heat, atmospheric moisture as well as soil moisture.

(iii) Its main aim is to control pest attack by controlling water, light & temperature.

(iv) Green house farming facilitates getting maximum product from land. It assists in getting maximum economic benefit

(e) Greenhouses are used on large scale for growing flowers like lily & gerbera to igive maximum returns.

Question 2.
Market gardening:
Answer:
(i) Market gardening is a type of cultivation developed mainly as a result of urbanization & ready markets available in urban centres.

(ii) Farmers cultivate vegetables & other items in the vicinity1 of urban centres to cater to the demands of city dwellers.

(iii) The landholding is small. Use of irrigation, organic & chemical fertilizers, low investment, use of manpower, demand of markets, use of science & technology are the characteristics of market gardening.

(iv) It is dependent on good transport network. The quality & price of the product is determined by rapid transport. Hence this type of farming is also called truck farming.

Question 3.
Organic farming:
Answer:

(i) The nutrient requirements of the crops is fulfilled by soil & therefore replenishment of used up nutrients is necessary.

(ii) Nutrients are also used abundantly to increase the yield. Organic fertilizers are prepared for this purpose

(iii) The litter should be decomposed in the ground. Grass like resbania or jute are also buried in the soil for making manures Cowdung & compost manures are used. Vermicompost is obtained from organic waste.

(iv) When farming is done using all the vestal matter mixed in the soil it is called organic farming

(v) The crop obtained from organic farming is high in quality.

Question 4.
Agrotourism:
Answer:

• Agrotourism is a new field in tourism.
• Vicinity – the area near or surrounding a particular place.
• In the tropics various types of agricultural products are cultivated. Hence there is greater scope for agrotourism.
• In agrarian countries the rural life, local customs & culture are utilized for agrotourism.
• City dwellers are curious about the farmers’ life & environment and many of them visit rural areas just to see this.
• Agrotourism is financially beneficial for the farmer & his village.

Question 5.
Importance of marketing system in India:
Answer:
The following points explain the importance of marketing systems in countries like India:

• Agriculture in India is scattered over vast areas.
• All farmers are not organized.
• Most of the farmers are economically weak & cannot market their production on their own.
• As farm produce is perishable, there has to be a proper arrangement for its sale.

Question 6.
Beekeeping.
Answer:

• Beekeeping is an important occupation with respect to agriculture
• It is undertaken to obtain honey & wax. In order to collect honey, bees hover around the plants that bear flowers.
• This promotes the process of pollination.
• As a result, the trees bear large number of fruits & the crop yields increase.

Question 7.
Pisciculture or Fish farming:
Answer:

• Farm ponds are dug out for the purpose of pisciculture. Water is stored in such ponds.
• Fish seeds are released in the ponds. For this seeds of fresh water species are used.
• In order to achieve the best growth of fish, scientific methods are employed.

Question 8.
Give comparative account of any two methods of irrigation
Answer:
Well irrigation, canal irrigation, drip & sprinkler irrigation, tank irrigation etc. are various methods of irrigation. Wells & canals have been used for irrigation since ancient times.

Well irrigation:-

• In this type of irrigation, a well is dug in the ground from which ground water is taken out for irrigation,
• The area required for digging wells is less,
• It is a cheap, dependable & popular method of irrigation in India.

Canal irrigation:-

• In this type of irrigation, dams are constructed on rivers & water of the river is stored in the reservoir,
• The stored water is then supplied to fields with the help of canals,
• Canal irrigation requires vast area for construction of dam as well as constructing network of canals,
• Canal irrigation is dependable but costly method of irrigation.

Question 9.
Sericulture:
Answer:

• Rearing of silkworm in order to obtain silk is sericulture.
• Leaves of the mulberry trees are the main food for these silk worms.
• Once planted the mulberry trees survive for a minimum period of 15 years.
• Silk thread is obtained from the cocoon of the silk. These threads are very fine & strong. They are used to weave silk cloth.

Balbharti Maharashtra State Board Class 7 History Solutions Chapter 2 India before the Times of Shivaji Maharaj Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 History Solutions Chapter 2 India before the Times of Shivaji Maharaj

Class 7 History Chapter 2 India before the Times of Shivaji Maharaj Textbook Questions and Answers

1. Name the following:

Question 1.
The Queen of Gondvana –
Answer:
Rani Durgavati

Question 2.
The son of Udaysingh –
Answer:
Maharana Pratap

Question 3.
The founder of Mughal dynasty –
Answer:
Babur

Question 4.
The first Sultan of the Bahamani kingdom–
Answer:
Hasan Gangu

Question 5.
The fighting force established by Guru Gobindsingh –
Answer:
Khalsa Dal

2. Find the odd one out:

Question 1.
Sultan Mahmud, Qutubuddin Aibak, Muhammad Ghuri, Babur
Answer:
Sultan Mahmud

Question 2.
Adilshahi, Nizamshahi, Sultanate,Baridshahi
Answer:
Sultanate

Question 3.
Akbar, Humayun, Shershah, Aurangzeb
Answer:
Shershah

3. Answer briefly:

Question 1.
How did the kingdoms of Vijaynagar and Bahamani emerge?
Answer:
(i) During the reign of Sultan Muhammad Tughlaq of Delhi, there were many revolts in the South against the central power of Delhi.
(ii) From these revolts arose the formidable Vijaynagar and Bahamani kingdoms.

Question 2.
What reforms did Mahmud Gawan make?
Answer:
(i) Mahmud Gawan strengthened the Bahamani kingdom.
(ii) He started paying the soldiers their salary in cash instead of through land grants.
(iii) He brought discipline in the army.
(iv) He introduced many reforms in the land revenue system. He opened a Madarsa at Bidar for Arabic and Persian studies.

Question 3.
Why did it become impossible for the Mughals to strengthen their base in Assam?
Answer:
(i) While Aurangzeb ruled, the Ahoms had a prolonged struggle with the Mughals.
(ii) The Mughals attacked the Ahoms’ region.
(iii) The Ahoms united under the leadership of Gadadharsinha. Commander Lachit Borphukan gave an intense battle against the Mughals.
(iv) The Ahoms used the guerilla technique in the conflict against the Mughals.
(v) It became impossible for Mughals to create a strong base in Assam.

4. Write about them briefly in your own words.

Question 1.
Krishnadevaraya
Answer:
(a) Krishnadevaraya, ascended the throne of Vijaynagar in 1509 CE. He conquered Vijaywada, Rajmahendri and annexed the regions to his kingdom.
(b) He successfully took on the armies of the Sultans who had united under the leadership of the Bahamani Sultan Mahmud Shah.
(c) During his reign the Vijaynagar kingdom extended far and wide.
(d) He built the Hazar Ram temple and Vitthal temple in Vijaynagar.
(e) A scholar he wrote ‘Amuktamalyada’, a Telugu compendium on polity.
(f) Decline of the Vijaynagar kingdom began with his death in the year 1530 CE.

Question 2.
Chandbibi was murdered.
Answer:
(a) Chandbibi, the capable daughter of Husain Nizamshah of Ahmadnagar, bravely defended the fort displaying courage and valour.
(b) At this time, there was an internal strife among the factions of the Sardars in Nizamshahi’s kingdom resulting in the murder of Chandbibi.

Question 3.
Rani Durgavati
Answer:
(a) Rani Durgavati, bom in the dynasty Chandel Rajput became the queen of Gondvana after her marriage.
(b) She was an excellent administrator. Her struggle against the Mughals is important in Medieval history.
(c) After her husband’s death, Durgavati laid down her life but refused to surrender while fighting against Akbar.

5. Give reasons:

Question 1.
The Bahamani Kingdom disintegrated into five fragments.
Answer:
(a) After the death of Mahmud Gawan, factionsim increased among the Bahamani Sardars.
(b) The conflict with the Vijaynagar kingdom had an adverse effect on the Bahamani kingdom.
(c) The provincial Governors began to act more independently. This led to the disintegration of the Bahamani kingdom into five small power-Imadshahi of Varhad, Baridshahi of Bidar, Adilshahi of Bijapur, Nizamshahi of Ahmadnagar and Qutubshahi of Golconda.

Question 2.
Rana Sanga’s army was defeated.
Answer:
(a) After the battle of Panipat, Rana Sanga of Mewad brought all Rajput kings together.
(b) There was a battle between Babur and Rana Sanga at Khanua.
(c) Babur’s artillery and reserved force played a key role in this battle and Rana Sanga’s army was defeated.

Question 3.
Rana Pratap has become immortal in history.
Answer:
(a) After the death of Udaysingh, Maharana Pratap ascended the throne of Mewad.
(b) He continued the struggle for Mewad’s existence.
(c) Till the very end he struggled with Akbar to maintain his independence.
(d) He has become immortal in history due to his qualities of valour, courage, self-respect and sacrifice.

Question 4.
Aurangzeb imprisoned Guru Tegh Bahadur.
Answer:
(a) Guru Tegh Bahadur, protested strongly against Aurangzeb’s policy of religious intolerance.
(b) Aurangzeb imprisoned him and beheaded him in 1675.

Question 5.
The Rajputs fought against the Mughals.
Answer:
(a) Akbar had secured the cooperation of the Rajputs with his policy of amicable relations.
(b) Aurangzeb could not obtain the cooperation of Rajputs. After the death of Rana Jaswantsingh of Marwad, Aurangzeb annexed his kingdom to the Mughal empire.
(c) Durgadas Rathod crowned Jaswantsingh’s minor son of Ajitsingh of Marwad.
(d) Durgadas Rathod fought hard against the Mughals and continued his struggle against the Mughals for the existence of Marwad.

6. Complete the timeline.

Answer:

7. Using the internet, find out more about any one of the personalities you have studied here, and fill in the box below.

Activity

Obtain more information about the personalities mentioned in this chapter.Use reference books, the internet, newspapers, etc. Prepare a collage of the pictures information in your activity book and display it in the history cell.

Class 7 History Chapter 2 India before the Times of Shivaji Maharaj Additional Important Questions and Answers

Complete the sentences by choosing the appropriate words from the options given below:

Question 1.
‘Pal’ in the ______ was a famous dynasty in Bengal. (seventh century, eight century, ninth century)
Answer:
eight century

Question 2.
Prithviraj Chauhan belonged to _______ dynasty. (Rajput dynasty, Chauhan dynasty, Chola dynasty)
Answer:
Chauhan dynasty

Question 3.
The _____ period is considered to be the golden period of Marathi language. (Yadava, Rashtrakuta, Chola)
Answer:
Yadava

Question 4.
In the eleventh Century CE, the _____ began to invade India and reached the north-western frontier of India. (Afghans, Mughals, Turks)
Answer:
Turks

Question 5.
______ was the last Sultan and he was defeated by Babur, bringing the Sultanate to an end. (Muhammad Ghuri, Bulban, Ibrahim Lodi)
Answer:
Ibrahim Lodi

Question 6.
Hampi in today’s ______ was the capital of the kingdom of Vijaynagar. (Kerala, Karnataka, Tamil Nadu)
Answer:
Karnataka

Question 7.
Krishnadevaraya wrote ‘Amuktamalyada’, a Telugu Compendium on _______. (polity, economics, sociology)
Answer:
polity

Question 8.
______ was the first Sultan of the Bahamani kingdom. (Muhammad-bin-Tughlaq, Mahmud Gawan, Hasan Gangu)
Answer:
Hasan Gangu

Question 9.
In ______ the Sultanate of Delhi came to an end. (1526 CE, 1556 CE, 1605 CE)
Answer:
1526 CE

Question 10.
_______ was the Governor of Punjab under the Sultanate. (Babur, Ibrahim Lodi, Daulatkhan Lodi)
Answer:
Daulatkhan Lodi

Question 11.
_______ was the most powerful king of the Mughal dynasty. (Shahajahan, Akbar, Jahangir)
Answer:
Akbar

Question 12.
The struggle of Gondvana queen Durgavati against Mughals is important in ______ history. (modern, medieval, ancient)
Answer:
medieval

Question 13.
______ became the emperor in 1658 CE. (Shahajahan, Aurangzeb, Akbar)
Answer:
Aurangzeb

Question 14.
In the thirteenth century CE, the people of the Shaan community settled down in the valley of river ______. (Ganga, Brahmaputra, Yamuna)
Answer:
Brahmaputra

Question 15.
The ninth Guru of the Sikhs was ______.(Guru Gobind Singh, Guru Tegh Bahadur, Guru Nanak)
Answer:
Guru Tegh Bahadur

Question 16.
______ organised the Sikh youths into a fighting force called Khalsa Dal. (Guru Gobind Singh, Guru Tegh Bahadur, Guru Nanak)
Answer:
Guru Gobind Singh

Question 17.
Akbar had secured the co-operation of the ______ with his policy of amicable relations. (Rajputs, Marathas, Ahoms)
Answer:
Rajputs

Question 18.
In Maharashtra, the ______ Marathas offered stiff resistance to and defended their independence. (Babur, Humayun, Aurangzeb)
Answer:
Aurangzeb

Match the following:

Question 1.

Column ‘A’	Column ‘B’
(1) Imadshahi	(a) Bidar
(2) Baridshahi	(b) Ahmadnagar
(3) Adilshahi	(c) Golconda
(4) Nizamshahi	(d) Varhad
(5) Qutubshahi	(e) Bijapur

Answer:
1 – d
2 – a
3 – e
4 – b
5 – c

Name the following:

Question 1.
Two important dynasties among the Rajput dynasties in North India.
Answer:
(a) The Gahadwal dynasty
(b) Parmar dynasty

Question 2.
Eminent rulers belonging to the Chola dynasty in Tamil Nadu.
Answer:
(a) Rajaraj I
(b) Rajendra I

Question 3.
The king belonging to the Hoysala dynasty.
Answer:
King Vishnuvardhan

Question 4.
The King who conquered the whole of Karnataka.
Answer:
King Vishnuvardhan

Question 5.
The Varkari movement emerged in
Answer:
The Yadava period

Question 6.
During his reign Rashtrakuta dynasty in Maharashtra the Rashtrakut power spread from Kanauj up to Rameshwar.
Answer:
Govind III

Question 7.
The last prosperous power before the period of Shivaji Maharaj.
Answer:
TheYadavas

Question 8.
The capital of Bhillam V of the Yadava dynasty which was near Aurangabad.
Answer:
Deogiri

Question 9.
The golden period of the Marathi Language.
Answer:
The Yadava period

Question 10.
The Arab General attacked the Sindh province in the eighth century.
Answer:
Muhammad-bin-Qasim

Question 11.
The power which began to invade India in eleventh century CE.
Answer:
The Turks

Question 12.
He invaded India many times and plundered the rich temples at Mathura, Vrindavan Kanauj and Somnath and carried away enormous wealth with him.
Answer:
Sultan Mahmud of Ghazni

Question 13.
In 1775 CE and 1178 CE, the Sultan of Ghur from Afghanistan who invaded India.
Answer:
Muhammad Ghuri

Question 14.
During his reign there were many revolts in the South against the central power of Delhi.
Answer:
Sultan Muhammad-bin-Tughluque

Question 15.
The brothers from South India who were Sardars in the service of Delhi Sultanate.
Answer:
(a) Harihar
(b) Bukka

Question 16.
The Hazar Ram temple and Vitthal temple were built in Vijaynagar during his reign.
Answer:
Krishnadevaraya

Question 17.
He defeated the army of the Sultan of Delhi.
Answer:
Hasan Gangu

Question 18.
The Chief Wazir of the Bahamani kingdom who started paying the soldiers their salaries in cash instead of giving land grants.
Answer:
Mahmud Gawan

Question 19.
The king of Farghana in Central Asia.
Answer:
Babur

Question 20.
After the battle of Panipat, he brought all Rajput kings together.
Answer:
Rana Sanga of Mewad

Question 21.
After ascending the throne of Mewad, he continued the struggle for Mewad’s existence.
Answer:
Maharana Pratap

Question 22.
The capable daughter of Husain Nizamshah of Ahmadn^gar who defended the fort of Ahmadnagar.
Answer:
Chandbibi

Question 23.
The Ahoms united under his leadership.
Answer:
Gadadharsinha

Question 24.
The commander who gave intense battle against the Mughals.
Answer:
Commander Lachit Borphukan

Question 25.
The ninth Guru of Sikhs who protested strongly against Aurangzeb’s policy of religious intolerance.
Answer:
Guru Tegh Bahadur

Question 26.
There was an attempt on the life of Guru Gobind Singh in 1708 CE at this place.
Answer:
Nanded

Question 27.
After his death Aurangzeb annexed his kingdom to the Mughal empire.
Answer:
Rana Jaswantsingh of Marwad.

Question 28.
In Maharashtra, Swaraj was established under his leadership.
Answer:
Shivaji Maharaj

Find out the odd man out:

Question 1.
Gadadharsinha, Rana Jaswantsingh, Durgadas Rathod, Ajit Singh.
Answer:
Gadadharsinha

Question 2.
Babur, Humayun, Krishnadevaraya, Jahangir
Answer:
Krishnadevaraya

Answer in one sentence:

Question 1.
Name the regions upto which the Gurjar- Pratihar power spread.
Answer:
The Gurjar-Pratihar power spread up to Andhra, Kalinga, Vidarbha, West Kathewad, Kanauj and Gujarat.

Question 2.
Which places did the Cholas conquer using their naval strength?
Answer:
The Cholas conquered the Maidive Islands and Sri Lanka using their naval strength.

Question 3.
In which period did the Mahanubhav Panth and the Varkari movement emerge?
Answer:
The Mahanubhav Panth and the Varkari movement emerged in the Yadava period.

Question 4.
Why did the Arab rulers turn towards India?
Answer:
The Arab rulers turned towards India to expand their empire.

Question 5.
Write the extent of the kingdom of Vij aynagar during Krishnadevaraya’s reign?
Answer:
During Krishnadevaraya’s reign, the kingdom of Vijaynagar extended from Cuttack in the east up to Goa in the West and from the Raichur Doab in the North up to the Indian Ocean in the South.

Question 6.
Who opposed Akbar when he tried to bring India under his central authority?
Answer:
When Akbar tried to bring India under his central authority he had to face the opposition of Maharana Pratap, Chandbibi and Rani Durgavati.

Question 7.
Which qualities of Maharana Pratap made him immortal in history?
Answer:
Maharana Pratap became immortal in history due to his qualities of valour, courage, self-respect and sacrifice.

Question 8.
Which regions together formed the Gondvana?
Answer:
Gondvana can be broadly said to comprise the eastern part of Vidarbha, part of Madhya Pradesh to its North, the Western part of today’s Chhattisgarh, Northern part of Andhra Pradesh and Western part of Odisha.

Question 9.
How did the Marathas defend their independence?
Answer:
Marathas offered stiff resistance to Aurangzeb and defended their independence.

Give reasons:

Question 1.
Babur invaded India.
Answer:
(a) The reigning Sultan of Delhi at that time was Ibrahim Lodi.
(b) Daulatkhan Lodi, was the governor of Punjab under the Sultanate.
(c) The relationship between Ibrahim Lodi and Daulatkhan Lodi was strained.
(d) Daulatkhan Lodi invited Babur to march to India. Taking this opportunity, Babur invaded India.

Write briefly in your own words:

Question 1.
The First Battle of Panipat
Answer:
(a) Ibrahim Lodi was the Sultan of Delhi and Daulat Khan Lodi was the Governor of Punjab.
(b) The relationship between Ibrahim Lodi and Daulatkhan Lodi became strained.
(c) Daulatkhan Lodi invited Babur to march on India.
(d) Taking advantage of this opportunity, Babur invaded India.
(e) To repel Babur’s invasion Ibrahim Lodi started with his army.
(f) There was a battle between Ibrahim Lodi and Babur on 21st April 1526 at Panipat.
(g) Babur defeated Ibrahim Lodi’s army. This is known as the First Battle of Panipat.

Answer briefly:

Question 1.
Write in brief about the conflict of the Mughals with the Marathas.
Answer:
(i) In Maharashtra, Sivaraj was established under the leadership of Shivaji Maharaj.
(ii) In his efforts to establish Swaraj, Shivaji Maharaj had to fight the Mughals too along with the other enemies.
(iii) Aurangzeb came down to the Deccan after the death of Chhatrapati Shivaji Maharaj with the intention of conquering the whole of South India.
(iv) But the Marathas offered stiff resistance to Aurangzeb and defended their independence.

Complete the following diagrams:

Question 1.

Answer:

Question 2.

Answer:

Complete the following table:

Question 1.

S.No	Political Power	Founders / Rulers	Capital

Answer:

S.No	Political Power	Founders / Rulers	Capital
(1)	Yadava	Bhillam V	Deogiri
(2)	Vijaynagar	Harihar & Bukka	Hampi
(3)	Bahamani	Hasan Gangu	Gulbarga
(4)	Mughal	Babur	Delhi

 

Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 3 Force and Pressure Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 8 Science Solutions Chapter 3 Force and Pressure

Class 8 Science Chapter 3 Force and Pressure Textbook Questions and Answers

1. Write proper word In the blank space:

Question a.
The SI unit of force is the ………..
(dyne, newton, joule)
Answer:
The SI unit of force is the newton.

Question b.
The air pressure on our body is equal to the …………. pressure.
(atmospheric, sea bottom, space)
Answer:
The air pressure on our body is equal to the atmospheric pressure.

Question c.
For a given object, the buoyant force in liquids of different ………… is ………….. .
(the same, density, different, area)
Answer:
For a given object, the buoyant force in liquids of different density is the same.

Question d.
The SI unit of pressure is ………………
(N/m³, N/m², kg/m², Pa/m²)
Answer:
The SI unit of pressure is N/m².

2. Make a match.

Question a.

Group ‘A’	Group ‘B’
1. Fluid	a. Higher pressure
2. Blunt knife	b. Atmospheric pressure
3. Sharp needle	c. Specific gravity
4. Relative density	d. Lower pressure
5. Hectopascal	e. Same pressure in all directions

Answer:

Group ‘A’	Group ‘B’
1. Fluid	e. Same pressure in all directions
2. Blunt knife	d. Lower pressure
3. Sharp needle	a. Higher pressure
4. Relative density	c. Specific gravity
5. Hectopascal	b. Atmospheric pressure

3. Answer the following questions in brief. 

Question a.
A plastic cube is released in water. Will it sink or come to the surface of water?
Answer:
It will come to the surface of water.
[Note: This is because its density is less than that of water. When it floats, the unbalanced force acting on it is zero.]

Question b.
Why do the load carrying heavy vehicles have large number of wheels?
Answer:
The pressure produced by a given force depends on the area of the surface on which the force acts. The greater the surface area, the less is the pressure produced. Load carrying heavy vehicles have large number of wheels so that the load (weight, force) is distributed over large surface area of the wheels in contact with the road. Hence, the pressure decreases and the tyres do not burst.

Try this :
Pressure of a liquid:

Activity 1:
Take a plastic bottle. Take a 10 cm long piece of a glass tube on which a rubber balloon can be fitted. Warm up one end of the glass tube and gently push it into the bottle at about balloon inflates. What is observed? The pressure of water acts on the side of the bottle as well.

[Note: Here, the area of cross section of the tube remains the same. As the level of the water in the bottle rises, the mass of the water increases resulting in increase in the weight. As the applied force increases, the pressure increases. Therefore, the balloon increases in size.]

Activity 2:
Take a plastic bottle. Pierce it with a thick needle (or with a hot nail) at the points 1, 2, 3 as shown in the Fig. Fill water in the bottle up to full height. A shown in the figure, water jets will be seen emerging and projecting out. The water jet emerging from the hole at the top will fall closest to the bottle. The jet from the lowest hole falls farthest from the bottle.

Also, jets coming out from the two holes at the same level fall at the same distance from the bottle. What is understood from this? At any one level, the liquid pressure is the same. Also, the pressure increases as the depth of the liquid increases.

Question c.
How much pressure do we carry on our heads? Why don’t we feel it?
Answer:
The air pressure at the sea level is about 101 × 10³ Pa. This is the pressure that we carry on our heads. The cavities in our body are filled with air, and arteries and veins are filled with blood. Their pressure balances the pressure due to the atmosphere. Hence, we don’t feel the atmospheric pressure.

4. Why does it happen?

Question a.
Why does it happen? A ship dips to a larger depth in freshwater as compared to marine water.
Answer:
The buoyant force acting on a body is proportional to the density of the fluid in which the body is immersed. The density of freshwater is less than that of marine water. Hence, the buoyant force on a body in freshwater is less than that in marine water. Therefore, a ship dips to a larger depth in freshwater as compared to marine water.

Question b.
Why does it happen? Fruits can easily he cut with a sharp knife.
Answer:

1. It is easy to cut vegetables. fruits with a sharp knife. A blunt knife does not work here.
2. The force exerted perpendicularly on a unit area is called ‘pressure’
   
3. Presently we are considering only the force acting on an area in a direction perpendicular to it.

Question c.
Why does it happen? The wall of a dam is broad at its base.
Answer:
1. The pressure at a point in a liquid is proportional to the height of the liquid column above it. Hence, the pressure of water in a dam is much greater at the bottom of the dam than at the top.
2. To withstand this high pressure, the wall of a dam is made stronger and thicker (broad) at the base than at the top.

Question d.
Why does it happen? If a stationary bus suddenly speeds up, passengers are thrown in the backward direction.
Answer:
1. When passengers sit or stand in a stationary bus, they are in a state of rest. When the bus suddenly speeds up, the lower (parts of their body in contact with the bus acquire the speed of the bus.
2. The upper parts of their body, however, continue to be in the state of rest due to inertia. Hence, they are thrown in the backward direction.

5. Complete the following tables. 

Question a.

Answer:
Using the formula,
density = mass/volume:

Mass (Kg)	Volume (m3)	Density (Kg/m3)
350	175	2
760	190	4

Question b.

Answer:
Using the formula, relative density = density of a metal/density of water:

Density of Metal (Kg/m3)	Density of water (Kg/m3)	Relative Density
5 × 103	103	5
8.5 × 103	103	4

Question c.

Answer:
Using the formula, pressure = weight/area:

Weight (N)	Area (m2)	Pressure (N.m-2)
800	0.04	20000
1500	500	3

6. The density of a metal is 10.8 × 10³ kg/m³. Find the relative density of the metal.

Question a.
The density of a metal is 10.8 × 10³ kg/m³. Find the relative density of the metal.
Solution:
Data: Density of the metal = 10.8 × 10³ kg/m³
density of water = 10³ kg/m³
relative density of the metal = ?

The relative density of the metal = 10.8.

7. The volume of an object is 20 cm³ and the mass is 50 g. The density of water is 1 gm^-3. Will the object float on water or sink in water?

Question a.
The volume of an object is 20 cm³ and the mass is 50 g. The density of water is 1 gm^-3. Will the object float on water or sink in water?
Solution :

It is greater than the density of water.
Hence, the object will sink in water.

8. The volume of a plastic-covered sealed box is 350 cm³ and the box has a mass 500 g. Will the box float on water or sink in water? What will be the mass of water displaced by the box?

Question a.
The volume of a plastic-covered sealed box is 350 cm³ and the box has a mass 500 g. Will the box float on water or sink in water? What will be the mass of water displaced by the box?
Solution:

It is greater than that of water.
Hence, the box will sink in water.
The volume of water displaced by the box (V) = the volume of the box = 350 cm³

∴ The mass of water displaced by the box = 1 g.cm^-3 × 350 cm³ = 350 g.

Project:

Question a.
Video record all the experiments (Try it) in this chapter with the help of mobile phone and send to others.

Class 8 Science Chapter 3 Force and Pressure Additional Important Questions and Answers

1. Rewrite the sentences after filling the blanks

Question 1.
The tendency of an object to remain in its existing state is called its …………. .
Answer:
The tendency of an object to remain in its existing state is called its inertia.

Question 2.
Pressure = ……………
Answer:

Question 3.
1 bar = ……………….. N/m².
Answer:
1 bar = 10⁵ N/m².

Question 4.
1 atmosphere = ………….. Pa.
Answer:
1 atmosphere = 101 × 10³ Pa.

Question 5.
The SI unit of density is …………. .
Answer:
The SI unit of density is kg/m³

Write proper word In the blank space:

Question 1.
According to Archimedes’ principle, the magnitude of the force of buoyancy acting on a body is …………. .
(Vρg, Vρ/g, Vρm, mρg)
Answer:
According to Archimedes’ principle, the magnitude of the force of buoyancy acting on a body is Vρg.

Question 2.
The pascal is the unit of ……………. .
(velocity, pressure, mass, force)
Answer:
The pascal is the unit of pressure.

Question 3.
Keeping the surface area constant, if the applied force is doubled, the pressure …………….. .
(becomes double, remains the same, becomes four times, becomes half)
Answer:
Keeping the surface area constant, if the applied force is doubled, the pressure becomes double.

State whether the following statements are True or False:

Question 1.
The density of water is 1000 g/cm³.
Answer:
False. [The density of water is 1000 kg/m³ (or 1 g/cm³)]

Question 2.
Force and weight have the same units.
Answer:
True.

Question 3.
Atmospheric pressure at sea level is about 10⁶ dynes/cm².
Answer:
True.

Question 4.
The buoyant force due to a liquid is proportional to the acceleration due to gravity.
Answer:
True.

Question 5.
Atmospheric pressure increases with altitude.
Answer:
False. (Atmospheric pressure decreases with altitude.)

Question 6.
Pressure due to a given force is directly proportional to the area on which the force acts.
Answer:
False. (Pressure due to a given force is inversely proportional to the area on which the force acts.)

Question 7.
When a body is completely immersed in a liquid, the buoyant force acting on it due to the liquid is proportional to the volume of the liquid displaced by the body.
Answer:
True.

Question 8.
The density of a material is useful to determine its purity.
Answer:
True.

Question 9.
One tends to slip over a banana peel on the street and one can slip due to mud are events that occur due to reduced friction.
Answer:
True.

Question 10.
Frictional force is electromagnetic in origin.
Answer:
True.

Identify the odd term:

Question 1.
Density, Pressure exerted by a gas, Mass, Force.
Answer:
Force. (Force is a vector quantity; other quantities are scalar quantities.)

Question 2.
Lactometer, Hydrometer, Voltmeter, Submarine.
Answer:
Voltmeter. (Its working is not based on Archimedes’ principle. The working of a lactometer, hydrometer and submarine is based on Archimedes’ principle.)

Rewrite the following table in such a way that Column 2 and Column 3 will match with Column 1:

Question 1.

Column 1	Column 2	Column 3
1. Pressure	Mass/volume	Specific gravity
2. Density	Force/area	Decreases with increase in height above the sea level
3. Atmos­pheric pressure	No unit	Useful to determine the purity of a substance
4. Relative density	The pascal	Decreases with increase in area

Answer:

Column 1	Column 2	Column 3
1. Pressure	Force/area	Decreases with increase in area
2. Density	Mass/volume	Useful to determine the purity of a substance
3. Atmos­pheric pressure	The pascal	Decreases with increase in height above the sea level
4. Relative density	No unit	Specific gravity

Answer the following questions in one sentence:

Question 1.
Which of the following has more inertia? A ₹ 10 coin and a ₹ 1 coin.
Answer:
A ₹ 10 coin has more inertia than a ₹ 1 coin.

Question 2.
Name the physical quantity expressed in pascal.
Answer:
Pressure is expressed in pascal.

Question 3.
State the SI unit of pressure.
Answer:
The SI unit of pressure is N/m², also called the pascal.

Question 4.
Name the property of a liquid due to which it exerts an upward force on an object immersed in it.
Answer:
Buoyancy is the property of a liquid due to which it exerts an upward force on an object immersed in it.

Question 5.
Name the principle used in designing ships and submarines.
Answer:
Archimedes’ principle is used in designing ships and submarines.

Question 6.
What is specific gravity?
Answer:
The specific gravity of a substance is another name used for relative density, i. e., the ratio of the density of the substance to the density of water.

Question 7.
State any one factor on which the pressure exerted by a liquid at a point inside the liquid depends.
Answer:
The pressure exerted by a liquid at a point inside the liquid depends on the density of the liquid.

Question 8.
State any one factor on which the buoyant force due to a liquid depends.
Answer:
The buoyant force due to a liquid depends on the density of the liquid.

Question 9.
Name the device used to determine the purity of a sample of milk.
Answer:
The lactometer is used to determine the purity of a sample of milk.

Question 10.
Name the device used to determine the density of a liquid.
Answer:
The hydrometer is used to determine the density of a liquid.

Question 11.
Name two instruments whose working is based on Archimedes’ principle.
Answer:
Working of the lactometer and hydrometer is based on Archimedes’ principle.

Answer the following questions:

Question 1.
Give three examples to show that a force acts on two bodies through an interaction between them.
Answer:

1. Consider a car at rest on a level (plane) road. If it is pushed from behind, it moves in the forward direction.
2. Iron nails get attracted to the poles of a magnet and stick to the magnet.
3. The moon revolves around the earth.

Question 2.
What is a contact force? Give one example.
Answer:
A force that acts through a direct contact of two objects or via one more object, is called a contact force.
Example: If a ball at rest on the ground is kicked, it starts moving.

Question 3.
What is a non contact force? Give one example.
Answer:
A force that acts between two objects even if the two objects are not in contact, is called a non contact force.
Example: The earth revolves around the Sun.

Use your brainpower!
Make a list of some more examples in which contact and non contact forces are applied. Write the types of force.
Answer:
1. Some examples in which contact forces are applied:

• to cut an apple with a knife (muscular force, frictional force)
• to lift a ball lying on the ground (muscular force, frictional force)

2. Some examples in which non contact forces are applied:

• the motion of the earth around the Sun (gravitational force)
• the motion of an electron around the nucleus of an atom (mainly the electric force).

Question 4.
In the following examples, state whether the force is a contact force or non contact force:

1. a reluctant dog is being pulled by his master
2. a boy playing football is kicking the ball away
3. when iron nails are brought near a magnet, they are attracted to the poles of the magnet and stick to the magnet
4. a coconut is falling from the coconut tree
5. when a comb is rubbed against hair, small pieces of paper kept on a table get attracted to the comb
6. when brakes are applied to a moving bicycle, it stops after some time

Answer:

1. contact force
2. contact force
3. non contact force
4. non contact force
5. non contact force
6. contact force.

Question 5.
Give one example in which frictional force is useful.
Answer:
While walking, we push the ground behind with our feet. In the absence of friction between the ground and the lower surface of our feet, we will slip and will not be able to walk.
[Note: Frictional force is electromagnetic in origin.]

Try this: 
Take two plastic bottles with rectangular shape. Close their openings by fitting the lids tightly. Keep two small bar magnets on them and fix them neatly using a sticking tape.

Fill a big plastic tray with water and leave the two bottles floating with magnets at the top. Take one bottle near the other. If the north pole of the magnet is near the south pole of the other magnet, the bottles will head towards each other, because unlike poles attract each other.

Observe what will happen when the directions of the bottles are changed. We can observe change in the motion of the bottles without any direct contact. This means that there exists a non contact force between the two magnets.

Observation: When the directions of the bottles are changed, if the north pole of one magnet is near the north pole of the other magnet (or the south pole of one magnet is near the south pole of the other magnet), the bottles will move away from each other because like poles repel each other.

Use your brain power!

Question.
You have learnt about static electricity in the previous standard. Electrostatic force is a non contact force. To verify this, which experiment will you perform?
Answer:

Do not switch on the fan in the room. Keep very small pieces of paper on the table. Rub a plastic comb against hair and bring it near the bits of paper. You will find that the bits of paper are attracted by the comb. The comb, on rubbing acquires electrostatic charge. It induces opposite charges on the bits of paper. Hence, the bits of paper are attracted by the comb.

Try this: 
Balanced forces and unbalanced force:

Take a cardboard box, tie thick string to its two sides and keep it on a smooth table as shown in Fig. Take the strings on both sides of the table. Tie weighing pans to the two ends. Keep equal masses in both the pans. The box does not move on the table.

If more mass is kept in one of the pans than in the other, the box starts moving in the direction of that pan. Equal gravitational force acts on both the pans when equal masses are kept in them. This means balanced forces act on the box, with effective force equal to zero as these are acting in opposite directions.

On the contrary, if more mass is kept in one pan than in the other, the box starts moving in the direction of the pan with more mass. When unequal forces are applied to the box on the two sides, an unbalanced force acts on the box resulting in imparting motion to the box.

Children playing tug of war pull the rope in their respective directions. If the pull of the force is equal on the two sides, the rope does not move. If the force is more on one side, the rope moves in that direction. This means that initially, the two forces are balanced; the rope moves in the direction of higher force when the forces become unbalanced.

Let us see one more example. When a big grain storage container is required to slide on the ground, it becomes easier if two persons push it rather than one person. When the force is applied by both in the same direction, the movement is easy. You may have experienced this. What do we understand from this example?

1. If several forces are applied on an object in the same direction, a force equal to their addition acts on that object.
2. If two forces are applied on one object in directions opposite to each other, a force equal to their difference acts on the object.
3. A force is expressed in magnitude and direction.

Force is a vector quantity. If more than one force are acting on a body, then the effect on the body is due to the net force. When a force is applied on a stationary object it moves, its speed and direction change. Similarly, a force is required to stop an object in motion.

An object can change its shape due to force. While kneading a dough made from flour, the dough changes its shape when a force is applied. A potter applies a force in a specific direction while shaping the pot. Rubber, when stretched, expands. There are many such examples. ,

Question 6.
What are balanced forces?
Answer:
If a body is acted upon by two forces, equal in magnitude, opposite in direction and having the same line of action, the forces are called balanced forces. Here, the net force acting on the body is zero.

Question 7.
What is an unbalanced force?
Answer:
If two or more forces act on a body such that their resultant is not zero, the resultant is an unbalanced force.
[Note: Unbalanced force acting on a body = mass of the body × acceleration of the body.]

Question 8.
Explain: Force has magnitude as well as direction. OR Force is a vector quantity.
Answer:
The effect of force applied to a body depends upon how much force we supply, i.e., the magnitude of the force, and the direction in which the force is applied. Consider a ball at rest on the ground. When ; we push it, it starts rolling. The greater the applied force, the greater is the speed acquired by the ball.

Consider a body moving in a straight line, If we apply a force in the direction of motion of the body, the speed of the body increases. On the contrary, if we apply a force in the direction opposite to that of motion of the body, the speed of the body decreases. These ( examples show that force has magnitude as well as direction, i.e., force is a vector quantity.

Question 9.
Explain the term balanced forces.
Answer:
Consider a rigid body acted upon by two forces, equal in magnitude, opposite in . direction and having the same line of action. These forces are called balanced forces as their net effect on the body is zero.
Example: A glass slab kept on a table is acted upon by two balanced forces: (i) the weight of the slab acting downward and (ii) the upward force on the slab due to the table. Their net effect on the slab being zero, the slab remains at rest.

Question 10.
Explain the term unbalanced force.
Answer:
A single force acting on a body is an unbalanced force. It produces acceleration in the body. If two or more forces act on a body such that their resultant is not zero, the resultant is an unbalanced force responsible for accelerating the body.
Example: When a ball lying on the ground is hit with a bat, the ball is set in motion by the applied force.

Question 11.
What will happen if the force is removed completely when an object acquires a certain speed?
Answer:
If the force is removed completely when an object acquires a certain speed, the object will move with the velocity it has at the instant the force is removed.

For example, a body moving with constant speed along a circular path in a horizontal plane will fly tangentially in the sense of motion if the centripetal force (the force directed towards the centre of the circle) is removed completely.

Always remember:

1. The tendency of an object to remain in its existing state is called its inertia.
2. This is why an object in stationary state remains in the same state and an object in motion remain in the state of motion in the absence of an external force.

Types of inertia:

1. Inertia of the state of rest: An object in the state of rest cannot change its state of rest due to its inherent property. This property is called the inertia of the state of rest.

2. Inertia of motion: The inherent property of an object due to which its state of motion cannot change, is called its inertia of motion. For example, a revolving’ electric fan continues to revolve even after it is switched off, passengers sitting in the running bus get aerk in the forward direction if the bus suddenly stops.

3. Directional inertia: The inherent property of an object due to which the object cannot change the direction of its motion, is called directional inertia. For example, if a vehicle in motion along a straight line suddenly turns, the passengers sitting in it are thrown opposite to the direction of turning.

Try this:
Activity 1:
Take a postcard and keep it on a glass. Keep a 5 Rupee coin on it. Now skilfully push the card. The coin straight away falls in the glass. Have you ever done this?
Answer:
Yes. (Explanation: The postcard moves forward due to the applied force and then falls due to the earth’s gravitational force. In the absence of adequate frictional force between the coin and the postcard, the coin does not move forward with the postcard, but straightaway falls in the glass due to the earth’s gravitational force.)

Activity 2: Hang a half a kg mass from a stand, with a string 1. Tie another string 2 to the mass and keep it hanging. Now pull the string 2 with a jerk. The string 2 breaks but the mass does not fall. Heavy mass does not move. Now pull the string 2 slowly. The string 1 breaks and the mass fall down. This is because of the tension developed in the string 2 due to the mass.

(Explanation: (1) As no force acts on the mass, it remains at rest due to inertia. (2) The transmission of force results in the tension in the string 1. As the string 1 cannot withstand it, it breaks and the mass falls down.)

Question 12.
What are the three types of inertia?
Answer:
Types of inertia:

• inertia of rest
• inertia of motion
• inertia of direction.

Question 13.
What is inertia of rest ? Give two examples of inertia of rest.
Answer:
The inherent property of a body by virtue of which it cannot change its state of rest is called the inertia of rest.
Examples:

1. When we dust a carpet, the carpet moves but the dust particles in it remain at rest due to inertia and hence get separated from the carpet. Hence, the carpet becomes clean.
2. When a bus starts suddenly, the passengers experience a backwarderk due to inertia.

Question 14.
What is inertia of motion? Give two examples of inertia of motion.
Answer:
The inherent property of a body by virtue of which it cannot change its state of motion is called the inertia of motion.
Examples:

1. When a fan is switched off, its blades continue to rotate for some time. Due to internal friction and friction with air, the blades of the fan stop rotating after some time.
2. Passengers in a bus experience a forwarderk when the bus stops suddenly due to application of brakes.

Question 15.
What is inertia of direction? Give two examples of inertia of direction.
Answer:
The inherent property of a body by virtue of which it cannot change its direction of motion is called the inertia of direction.
Examples:

1. While sharpening a knife, sparks fly off tangentially in the sense of motion from the grinding stone.
2. When a vehicle moves, the mud particles sticking to its wheels fly off tangentially in the sense of motion. Hence, mudguards are fitted to vehicles.

Question 16.
Why do we fall sideways when we are sitting in a bus and it takes a sharp turn?
Answer:
When we sit in a bus and the bus is in motion, we are in a state of motion in the same direction. When the bus takes a sharp turn, our body tends to maintain the state of motion in the straight line due to inertia. The portion of our body in firm contact with the seat acquires the motion along the curved path, but the upper portion of our body, tends to move in the initial direction of motion. Hence, we fall sideways.

Question 17.
What happens when you shake a wet piece of cloth? Explain your observation.
Answer:

1. When we shake a wet piece of cloth, water droplets come out.
2. Initially, the wet piece of cloth is at rest. When the cloth is shaken, it is accelerated, but the water droplets in it, due to inertia, tend to maintain the state of rest. Hence, the droplets come out.

Question 18.
If brakes are suddenly applied to a moving car, the passengers in the car are pushed in the forward direction. Explain why.
Answer:
1. The passengers in a moving car have the same velocity as that of the car. When brakes are suddenly applied to the car, it stops suddenly and the lower parts of the passengers’ bodies in contact with the seats, come to rest.

2. The upper parts of their bodies, however, continue to be in a state of motion due to inertia. Hence, the passengers are pushed in the forward direction.

Question 19.
A person alighting from a moving train is likely to fall in the direction of motion of the train. Explain why.
Answer:

1. A person in a moving train has the same velocity as that of the train. After alighting from the moving train his feet come to rest on the platform.
2. However, due to inertia, the upper part of his body continues to be in a state of motion in the direction of motion of the train. Hence, he is likely to fall in the direction of motion of the train.

Try this: 

Activity 3: Take some sharp pointed nails and push them into a wooden plank by hammering on their heads. Now take? a nail and hold it with its head on the plank and hammer it down from the pointed end. When pressing the drawing pins into a drawing board, they get into the board easily. By applying a force using the thumb one can push the pins into the boards. On the contrary, while pressing ordinary pins into the board with a thumb, the thumb may get hurt.

What does this simple experiment tell?
The nail easily penetrates into wood from its pointed end. From this you will notice that when a force is applied on the head of the nail, it is easy to hammer it into the plank.
Explanation: The less the area of the surface on which the force is applied, the greater is the effect of the force.

Question 20.
Define pressure.
Answer:
The force exerted perpendicularly on a unit area is called pressure.

Use your brain power!

Question 1.
It is easy to cut vegetables, fruits with a sharp knife. A blunt knife does not work here. Why does this happen?
Answer:
The effect of a given force varies l inversely as the area of the surface on ( which the force is applied. The less the surface area, the greater is the effect of the force. The cutting edge of a sharp ’ knife has less cross sectional area relative to that of a blunt knife. Hence, it is easy to cut vegetables, fruits with a sharp knife, rather than with a blunt knife. For a given force, pressure is inversely proportional to the area of the surface on which the force acts.

Question 21.
State the formula for pressure, Hence, determine the unit of pressure.
Answer:

The SI unit of force is the newton (N) and that of area is m². Therefore, the SI unit of pressure is N/m². It is called the pascal (Pa). 1 Pa = 1 N/m².
[Note: The unit pascal is named in honour of Blaise Pascal (1623-62), French mathematician, physicist and philosopher.]

Question 22.
State the CGS unit of pressure. State the relation betweeen the SI and CGS units of pressure.
Answer:
The CGS unit of pressure is the dyne/cm².
IN = 105 dynes, 1m² = (102 cm)² = 104 cm² 1 Pa = 1 N/m² = 105 dynes/104 cm² = 10 dynes/cm².

Question 23.
State the factors on which pressure depends.
Answer:
Pressure depends on the applied force and the area of the surface on which the force is applied.

Question 24.
Explain with a suitable example that pressure varies inversely as the area of the surface on which the force is applied, if the force remains constant.
Answer:
The tip of a pointed nail has an extremely small area, while that of a blunt nail has a comparatively large area. A given force creates a large pressure on the pointed nail and it can be easily hammered into the wood, while a very less pressure is created on the blunt nail and it cannot be easily hammered into the wood.

This shows that pressure varies inversely as the area of the surface on which the force is applied, if the force remains constant. If the same force is applied to surfaces having different areas, the pressure is more on the surface having a smaller area.

[Note: The bottom surface of a camel’s feet is broad. Hence, the camel’s weight acts on a large surface area. This reduces the pressure on the sand. Hence, the camel’s feet do not penetrate deep into the sand. Therefore, it becomes easier for the camel to walk on sand.]

Question 25.
With neat diagrams, describe an experiment to show that pressure increases if the surface area is decreased, keeping the applied force the same.
Answer:
Take a brick measuring 20 cm x 10 cm x 5 cm. Take some clay in a glass trough. Add water to it and knead it into a soft dough. Place the brick on the dough with one of its faces measuring 20 cm x 10 cm in contact with the dough. Observe how deep the brick penetrates into the dough.

Clean the brick and place it on the dough with one of its faces measuring 10 cm x 5 cm in contact with the dough. Observe how deep the brick penetrates into the dough. You will find that the brick penetrates deeper in this case than that in the first case.

• In the first case, the weight of the brick acts on a surface area of 200 cm².
• In the second case, the weight of the brick acts on a surface area of 50 cm².
• This shows that pressure increases if the surface area is decreased, keeping the applied force the same.

Question 26.
State the unit for pressure used in atmospheric science. How is it related to the unit pascal?
Answer:
In atmospheric science, the unit used for pressure is the bar. 1 bar = 10 Pa (pascal).

Try this:

Question 1.
Do the activity as depicted in Figure What is seen?
Answer:
In Fig.(a), the plank is horizontal. In Fig.(b), four books are placed side by side on the plank. The plank bends slightly due to the pressure produced by the weight of the books.

In Fig.(c), the four books are placed one above the other in the middle of the plank. Here the area of the surface of the plank on which the force acts is reduced by a factor of four relative to the earlier case. Hence, the plank bends considerably.
[Note: This shows that for a given force, pressure varies inversely as the area of the surface on which the force acts.]

Use your brainpower! 

Question 1.
You must have seen a vegetable vendor carrying a basket on her head. She keeps a twisted piece of cloth on the head, below the basket. How does it help?
Answer:
Keeping a twisted piece of cloth on the head increases the area of the surface on which the weight of the basket containing vegetables acts. Hence, the pressure produced by the force (weight) is reduced and it becomes easier to carry the basket.

Question 2.
We cannot stand at one place for a long time. How then can we sleep on a place for 8 and odd hours?
Answer:
When we stand, our weight acts on relatively small surface area, resulting in increased tension on the muscles of our legs. Hence, we cannot stand at one place for a long time. When we sleep, our weight acts on relatively large surface area, resulting in comparatively reduced tension. Therefore, we can sleep on a place for 8 and odd hours.

Question 3.
For skiing on ice, why are long flat skis used?
Answer:
The pressure produced by a given force depends on the area of the surface on which the force acts. The greater the surface area, the less is the pressure produced. The skis used to slide over snow are long and flat so that the area is increased and hence the pressure is decreased. This makes it easier to slide over snow.

Question 27.
Why do the blades of a pair of scissors have sharp edges?
Answer:
The pressure produced by a given force depends on the area of the surface on which the force acts. The less the surface! area, the greater is the pressure produced, The blades of a pair of scissors have sharp edges so that the area is decreased and hence the pressure is increased. This makes cutting • an object such as cloth easier.
[Note: Answers to questions such as why is the blade of an axe sharp? or why is the blade of a saw sharp? can be written on the basis of the answer given above.]

Question 28.
Why does a needle have s sharp point?
Answer:
The pressure produced by a given force depends on the areas of the surface on which the force acts. The less the surface area, the greater is the pressure produced. A needle has a sharp point so that the area is decreased and hence the pressure is increased. This makes the action of piercing easier.

Question 29.
Why do school bags have broad shoulder straps?
Answer:
The pressure produced by a given force depends on the area of the surface on which the force acts. The greater the surface area, the less is the pressure produced. School bags have broad shoulder straps so that the weight of the bag is distributed over a large surface area thereby decreasing the pressure on the shoulders of the student carrying the bag.

Question 30.
How will the pressure change if the area is doubled keeping the force the same?
Answer:
If the area is doubled, keeping the force the same, the pressure will become half the initial pressure.

Question 31.
How will the pressure change if the force is doubled, keeping the area the same?
Answer:
If the force is doubled, keeping the area the same, the pressure will become double the initial pressure.

Question 32.
State the characteristics of the pressure due to a liquid (or a fluid in general).
OR
Write a short note on the pressure due to a liquid (a fluid in general).
Answer:
Characteristics of the pressure due to a liquid (or a fluid):

1. The pressure at a point in a liquid (or a fluid) is due to the weight of the liquid (fluid) column above that point.
2. It acts on all sides of the container.
3. At a given depth it is the same in all directions.
4. It is independent of the size and shape of the container.
5. It is proportional to the height of the liquid (fluid) column above the given point.
6. It is proportional to the density of the liquid (fluid).
7. It is proportional to the acceleration due to gravity at the given place.

[Note: The pressure exerted by a liquid (or gas or fluid) at a depth h below the free surface of the liquid = hpg, where p is the density of the liquid (or gas or fluid) and g is the acceleration due to gravity.]

Question 33.
Give two examples to show that air exerts equal pressure in all directions.
Answer:

1. When air is filled in a balloon, it acquires its characteristic shape such as round or oval.
2. When a bicycle tube is filled with air, it acquires its characteristic (tube-like) shape throughout. This shows that air exerts equal pressure in all directions.

Question 34.
Whatisafluid?Givetwoeamples.
Answer:
A fluid is a substance which can flow.
Examples:

1. Water (liquid)
2. Air (gas)

[Note: Liquids and gases together are called fluids. Gases have very low viscosity compared to liquids. A liquid with low viscosity flows easily. A liquid with high viscosity does not flow easily.]

Question 35.
Take two rubber balloons. Fill one with water and blow air into the other. Now prick both balloons with a pin. What do you observe?
Answer:
Water and air both come out of the balloons. Air escapes quickly compared to water and produces a loud sound.

Question 36.
State the characteristics of pressure exerted by a fluid.
OR
Write a short note on pressure exerted by a fluid.
Answer:
Characteristics of pressure exerted by a fluid:

1. A fluid due to its weight, exerts pressure on the base as well as the walls of the container that holds it.
2. A fluid exerts pressure on a body immersed in it.
3. The pressure exerted on any confined mass of fluid is transmitted undiminished in all directions.

[Note: The pressure exerted by a fluid is a scalar quantity.]

Question 37.
Take an empty can. Pour small quantity of water in it. Boil this water for a few minutes until the steam has driven out most of the air. Now close the can with the stopper tightly. Allow it to cool by pouring cold water over it. What do you observe?
Answer:
The can gets gradually crushed.
[Note: The steam inside the can condenses to form water as the can cools. Therefore, the pressure inside the can becomes much less than the external pressure of the air. Hence, the can gets crushed.]

Question 38.
Put a folded newspaper on a plastic bag. Blow air into the bag. What do you observe?
Answer:
The plastic bag inflates as air is blown into it. This raises the folded news¬paper put on the bag.

Question 39.
What is meant by atmospheric pressure?
Answer:
The earth is surrounded by air from all sides. This layer of air is called the atmosphere. Its density is high up to about 16 km from the earth’s surface. Beyond that, up to about 400 km, its density is very low. Air, due to its weight, exerts pressure on the surface of the earth.

The pressure exerted by air or the atmosphere surrounding the earth is known as the atmospheric pressure. It is the ratio of the weight of the air to the area of the surface of the earth. It decreases with altitude as the density of air decreases with altitude and also the weight of the air column above a given place.
[Note: At sea level the atmospheric pressure is about 105 Pa. We do not feel it because the pressure of blood and other fluids in our body balances it.]

Question 40.
State the relation between 1 atmosphere and the pascal.
Answer:
1 atmosphere = (about) 101 × 10³ Pa (pascal)
[Note: The air pressure at the sea level is (about) 1 atmosphere.
1 atmosphere = 101325 Pa.
1 bar = 10³ mbar (millibar)
1 mbar w 10³ Pa (hectopascal)
Atmospheric pressure is expressed in mbar or hectopascal (hPa).]

Use your brain power!

Question 1.
At the sea level the atmospheric pressure 101 × 10³ Pa is acting on a table top of size 1 m². Under such a heavy pressure, why doesn’t the table top crumble down?
Answer:
The air below the table top exerts pressure 101 × 10³ Pa on it in the upward direction. Hence, the table top doesn’t crumble down.

Question 41.
Think – Why?
Question i.
Some people feel their ears popping at the top of a mountain.
Answer:
Atmospheric pressure decreases with altitude. At the top of a mountain, it becomes less than the internal pressure in the ear. Hence, some people feel their ears popping at the top of a mountain.

Question ii.
Some people feel breathless as they climb higher and higher on a mountain.
Answer:
Atmospheric pressure decreases with altitude. Hence, some people feel breathless as they climb higher and higher on a mountain.

Question iii.
We can enjoy a cold-drink or fruit juice with the help of a straw but can we imagine drinking a cold-drink or fruit juice on the moon using a straw?
Answer:
When we suck air in the straw, the pressure of the air in the straw becomes less than that of the outside air on the cold drink or fruit juice in the bottle (or the glass). Hence, the cold drink or fruit juice rises in the straw and enters our mouth. We can then drink it. There is no atmosphere on the moon. Hence, it is not possible to enjoy a cold drink or fruituice on the moon by using a straw.

Question iv.
People are often advised not to carry fountain pens while travelling by air.
Answer:
The ink in a fountain pen (filled at sea level at atmosphere pressure) may come out through its mouth while travelling by air if the outside pressure becomes less than the pressure in the ink holder of the pen. This can spoil the clothes/purse/bag. Hence, people are often advised not to carry fountain pens while travelling by air.

Question 42.
Why do some people have earache when they travel by an aeroplane?
Answer:
When an aeroplane descends at a high speed, there is an increase in air pressure. This increases the pressure on the ear drum. Hence, some people have earache when they travel by an aeroplane.

Question 43.
Explain why a person may bleed from the nose when at a great height above the sea level.
Answer:
The pressure exerted by the blood in blood capillaries is slightly more than the atmospheric pressure and acts in a direction opposite to that of the atmospheric pressure. Atmospheric pressure decreases with height and at a great height above the sea level, it is very low.

As a result, there arises a difference in the internal and external pressures on the walls of the cells and blood capillaries. If the difference is large, it may cause the cell wall and the blood capillaries to burst. Thus, the capillaries in the nose (and ear) may burst causing bleeding.

Question 44.
When a rubber sucker is pressed onto a flat glass surface, it sticks tightly on the surface. Why? You need a large force to separate it from the surface. Why?
Answer:
When a rubber sucker is pressed onto a flat glass surface, practically all the air between the surfaces of the sucker and the glass is pushed out. The air pressure there becomes much less than the atmospheric pressure. Hence, the sucker sticks to the glass due to the external atmospheric pressure. The atmospheric pressure is about 105 Pa. It is very large. Hence, to work against it to separate the sucker from the glass, a large force is needed.

Question 45.
Describe a simple experiment to demonstrate atmospheric pressure.
Answer:
Fill a glass completely with water (to its brim) and cover it with a flat and stiff card paper (or a piece of glass). Holding your palm on the card, turn the glass upside down and take the palm away from the card.

You will find that the water does not spill. The atmospheric pressure on the card (acting upward) is greater than the pressure of the water in the glass (acting downward). Hence, the water in the glass does not spill.

Question 46.
Explain the working of an ink dropper.
[Application]
Answer:
An ink dropper consists of a tube of glass or plastic, with one end tapering to a narrow opening and the other end fitted with a small rubber bulb. When the narrow open end is dipped into the ink and the rubber bulb is pressed, some air in the tube escapes through the open end. This reduces the air pressure inside the dropper.

On releasing the bulb, the atmospheric pressure on the ink pushes the ink into the dropper. The dropper is then taken out and its open end is held over the open barrel of the pen. The bulb is then pressed so that the ink in the dropper enters the pen.
[Note: The medicine dropper works in the same manner.]

Question 47.
Why is the opening of a dropper very narrow?
Answer:
The pressure produced by a given force is inversely proportional to the area of the surface on which the force acts. The opening of a dropper is very narrow. Hence, its area of cross-section is very small. As a result, even if the dropper has a small amount of ink it, its pressure can equal the atmospheric pressure. As the opening is narrow, it is easier to transfer the ink to the pen. The possibility of ink spilling is very low.

Question 48.
What is the characteristic of the cap of eye drop bottles?
Answer:
The cap of an eye drop bottle is fitted with a dropper.

Question 49.
Explain the working of a syringe
used by children when they play with coloured water. [Application]
Answer:
As shown in the figure, a syringe used by children when they play with coloured water consists of a cylinder made of plastic or metal fitted with a piston. One end of the cylinder is in the form of a narrow

tube. The snugly fitting piston can slide in , and out smoothly. The rod connected to the i piston passes through a hole in the centre of the lid and has a handle at the other end. When the tip of the narrow tube is dipped in coloured water (or any other liquid) and the piston is pushed towards the tip, up to the bottom, most of the air in the cylinder escapes through the tube, reducing the pressure.

When the piston is moved up, the coloured water rises in the part of the cylinder below the piston due to the atmospheric pressure. Finally, the inner pressure equals the atmospheric pressure and no more coloured water enters in or comes out.

To spray the coloured water, the tube is taken out and the piston is moved towards the opening of the tube. As the inner pressure is now greater than the atmospheric pressure, the coloured water gushes out of the narrow opening of the tube.

Question 50.
How does the doctor’s syringe work?
Answer:
As shown in the figure, a syringe used by children when they play with coloured water consists of a cylinder made of plastic or metal fitted with a piston. One end of the cylinder is in the form of a narrow

tube. The snugly fitting piston can slide in , and out smoothly. The rod connected to the i piston passes through a hole in the centre of the lid and has a handle at the other end.

When the tip of the narrow tube is dipped in coloured water (or any other liquid) and the piston is pushed towards the tip, up to the bottom, most of the air in the cylinder escapes through the tube, reducing the pressure. When the piston is moved up, the coloured water rises in the part of the cylinder below the piston due to the atmospheric pressure.

Finally, the inner pressure equals the atmospheric pressure and no more coloured water enters in or comes out. To spray the coloured water, the tube is taken out and the piston is moved towards the opening of the tube. As the inner pressure is now greater than the atmospheric pressure, the coloured water gushes out of the narrow opening of the tube.

The tip of a syringe is fitted with a very fine and hollow needle. The required quantity of medicine can be taken in the syringe with the help of the piston. The medicine can then be injected into the body of a patient using the needle and the piston.

Question 51.
Explain the origin of pressure due to a gas enclosed in a container.
Answer:
Molecules of a gas are in a state of continuous random motion. These molecules possess energy due to motion. When the molecules collide with a wall of the container, they rebound. A large number of molecules collide with the wall every second. Hence, a significant force is exerted on the wall. Pressure is the force per unit surface area. Thus, a pressure is exerted by the gas on a wall of the container.

Try this: 

Buoyant force:
Take a plastic bottle and fix the lid tightly. Now place it in wafer and see. It will float on water. Try and push it into the water. Even when pushed, it continues to float. This experiment can also be done with a plastic hollow ball. Now fill the bottle with water to the fullest capacity and close the lid, and release in water. The bottle will float inside the water. Why does this happen?

The empty plastic bottle floats on the surface of water. On the contrary, the bottle full of water floats inside water but does not go to the bottom. The weight of the empty bottle is negligible as compared with the weight of the water inside.

Such a bottle with water neither floats on the surface, nor does it go to the bottom. This means the force due to gravity acting downwards (fg), must have been balanced by an opposing force in the upward direction (fb) on the bottle filled with water. This force must have originated from the water surrounding the bottle. The upward force acting on the object in water or other fluid or gas is called buoyant force (fg).

Question 52.
Define buoyant force.
Answer:
The upward force acting on the object in water or other fluid or gas is called the buoyant force.

Question 53.
State the factors on which the buoyant force depends.
Answer:
The buoyant force depends upon the volume of the object immersed in the fluid (V), the density of the fluid (ρ1) and the acceleration due to gravity (g) at that place.
[Note: Magnitude of the buoyant force = Vρ1 g.]

Use your brain power!

Question.
While pulling a bucket from a well, the bucket full of water immersed fully in water appears to weigh less than when it has been pulled out of water. Why?
Answer:
1. When a bucket full of water is immersed in water, the net force acting on the bucket = weight of the bucket full of water-the buoyant force exerted by the water on the bucket. The buoyant force due to a fluid is proportional to the density of the fluid.

2. The density of water is much greater than that of air. Therefore, the buoyant force acting on a bucket full of water while it is in water is much greater than that when it is out of water, i.e., in air. Hence, it appears to weigh less, while it is in water than when it has been pulled out of water.

Try this:

Question 1.
Take a piece of thin aluminum sheet and dip it in water in a bucket. What do you observe?
Answer:
It sinks in the water.

Question 2.
Now shape the same piece of aluminium into a small boat and place it on the surface of water. It floats, isn’t it?
Answer:
Yes, the boat floats on the surface of water.

Question 54.
A lemon sinks in a glass filled with water but it floats when we stir in two spoons of salt in the water. Explain why.
Answer:
When salt is dissolved in water, the density of the water increases. The buoyant force is proportional to the density of the liquid. Hence, when the lemon is immersed in the water containing salt, the magnitude
of the buoyant force acting on the lemon becomes greater than the magnitude of the weight of the lemon. Therefore, it floats in water.

Do you know?

How is it decided that an object left in a liquid will get sink in the liquid, will float on the surface, or will float inside the liquid?
1. The object floats if the buoyant force is larger than its weight.
2. The object sinks if the buoyant force is smaller than its weight.
3. The object floats inside the liquid if the buoyant force is equal to its weight. Which forces are unbalanced in the above cases?
Answer:
Unbalanced force:
1. Magnitude of the unbalanced force acting on the object = magnitude of the buoyant force on the object-magnitude of the weight of the object. The direction of the unbalanced force is the direction of the buoyant force.

2. Magnitude of the unbalanced force on the object = magnitude of the weight of the object – magnitude of the buoyant force on the object. The direction of the unbalanced force is the direction of the weight of the object.

3. Here, the unbalanced force is zero.

Try this:

Take a long rubberband and cut it at one point. At one of its ends tie a clean washed stone or a 50 g weight as shown in Figure
Now hold the other end of the rubberband and make a mark there. Keep the stone hanging in air and measure the length of the rubberband from the stone to the mark made earlier.

Now take water in a pot and hold the rubberband at such a height that the stone sinks in it. Again measure the length of the rubberband up to the mark. What is observed? This length is shorter than the earlier length. While dipping the stone in water, length of the stretched rubber gets slowly reduced and is minimum when it sinks completely. What could be the reason for a shorter length of the rubberband in water?

When the stone is sunk in water, a buoyant force acts on it in the upward direction. The weight of the stone acts downwards. Therefore, the force which acts on it in the downward direction is effectively reduced.
(This decreases the downard force on the rubberband. Hence, its length decreases.)

Question 55.
State Archimedes’ principle.
Answer:
Archimedes’ principle: When an object is partially or fully immersed in a fluid, a force of buoyancy acts on it in the upward direction. This force is equal to the weight of the fluid displaced by the object.
[Note: The two forces mentioned here are equal in magnitude and opposite in direction.]

Question 56.
Using Archimedes’ principle, determine the magnitude of the buoyant force.
Answer:
Let m = mass of the body (object) immersed in the fluid, V = volume of the body, ρ = density of the body, ρ1 = density of the fluid, g = magnitude of the acceleration due to gravity. Suppose that the body is completely immersed in the fluid. Then the volume of the fluid displaced by the body = V. According to Archimedes’ principle, magnitude of the buoyant force = magnitude of the weight of the fluid displaced by the body = mass of the displaced fluid × g = volume of the displaced fluid × density of the fluid × g
(as density = mass/volume)

If the body is partially immersed in the fluid, the volume of the fluid displaced by the immersed part of the body = xV ; here 0 < x < 1.
In this case, the magnitude of the buoyant force

Question 57.
Using the formula for the magnitude of the buoyant force, state under what conditions the body will
1. sink in the fluid
2. float in the fluid
3. remain in equilibrium anywhere within the fluid.
Answer:
Magnitude of the buoyant force on the body = mg \(\left(\frac{\rho_{1}}{\rho}\right)\)
= magnitude of the weight of the body × \(\left(\frac{\rho_{1}}{\rho}\right)\)
1. If the density of the fluid (ρ1) is less than the density of the body (ρ), the magnitude of the buoyant force on the body will be less than the magnitude of the weight of the body. Therefore, the body will sink in the fluid.|

2. If the density of the fluid is greater than that of the body, the magnitude of the buoyant force on the body will be greater than that of the weight of the body. Therefore, the body will float in the fluid.

3. If the density of the fluid is equal to that of the body, the magnitude of the buoyant force on the body will be equal to that of the weight of the body. Therefore, the body will remain in equilibrium anywhere within the fluid.

Use your brain power!

Question.
Explain the observations in the earlier experiments according to the Archimedes’ principle.
Answer:
The increase in the length of the rubberband (y) is proportional to the downward force (f) acting on it.
1. When the stone tied to the rubberband is hanging in air, the magnitude of the buoyant force exerted by air on the stone is negligible compared to that of the weight of the stone. Hence, ignoring it, we have f = fg = mg, where m is the mass of the stone and g is the acceleration due to gravity.

2. When the stone is immersed partially in water, f = fg – fb, where fb is the magnitude of the buoyant force exerted by water on the stone.
Now, fg = Vρg and fb = xVρwg, where V = volume of the stone, ρ = density of the stone, xV= volume of the water displaced by the part of the stone immersed in water = volume of the part of the stone immersed in water (x < 1) and ρ = density of water.

This shows that as the stone is gradually lowered in water, x goes on increasing and hence/goes on decreasing. Therefore, elongation (y) of the rubberband goes on decreasing, i.e., the length of the rubberband goes on decreasing.

3. When the stone is completely immersed in water, x becomes maximum, equal to 1. Here, f = fg \(\left(1-\frac{\rho_{\mathrm{W}}}{\rho}\right)\). This is the minimum value of. Here, the elongation of the rubberband is minimum, i.e., the length of the rubberband is minimum.

Question 58.
State the applications of Archimedes’ principle.
Answer:
Archimedes’ principle is used in the construction of ships and submarines. The working of the lactometer and hydrometer is based on Archimedes’ principle.
[Note: The hydrometer is used to determine the density or relative density of a liquid.]

Question 59.
If a spring balance is used to weigh a body, will the weight of the body be the same in vacuum and air? Explain why.
Answer:
When a body is suspended in air, the buoyant force acts on the body. Hence, the magnitude of the net downward force on 1 the body = the magnitude of the weight of the body – the magnitude of the buoyant force on the body. Hence, when a spring balance is used to weigh a body, the weight of the body in air is less than that in vacuum.

Question 60.
What is density of a substance? I Obtain its SI unit.
Answer:
The density of a substance is the ratio of its mass to volume.
The SI unit of density = \(\frac{\text { the SI unit of mass }}{\text { the SI unit of volume }}\) = kg/m³
[Note: Density is useful in determining the purity of a substance. The CGS unit of density is g/cm³.
1 kg/m³ = 10³g/(100 cm)³ = 10^-3g/cm³
∴ 1g/cm³ = 1000 kg/m³]

Question 61.
What is relative density of a substance?
Answer:
The relative density of a substance is the ratio of its density to the density of water.
[Note: Relative density is also called specific gravity. It is a ratio of two equal (same) physical quantities. Hence, it has no unit.]

Question 62.
A piece of wood floats both in water and kerosine. In which liquid does it sink more during floating? Why?
Answer:
The piece of wood sinks more in kerosine than in water during floating. The density of kerosine is less than that of water. The buoyant force on a body is proportional to the density of the liquid in which the body is immersed. When a body floats, the magnitude of the buoyant force acting on the body is equal to that of the weight of the body.

Hence, the volume of the liquid displaced by a floating body is inversely proportional to the density of the liquid. As a result, when a piece of wood floats in kerosine, it displaces greater volume of kerosine compared to the volume of water displaced when the piece of wood floats in water. Hence, it sinks more in kerosine than in water.
[Note: When a body floats in a liquid fb = fg
∴ Vρ1g = Vbρbg
∴ The volume of the liquid displaced by the body is V = Vb \(\frac{\rho_{\mathrm{W}}}{\rho_{1}}\), where Vb is the volume of the body, ρb is the density of the material of the body and ρ1 is the density of the liquid. Thus, V ∝ 1 /ρ1]

Question 63.
State whether the body will float or sink in a liquid if the density of the body is 1. greater than that of the liquid 2. less than that of the liquid 3. equal to that of the liquid.
Answer:

1. The body will sink in the liquid if the density of the body is greater than that of the liquid.
2. The body will float in the liquid if the density of the body is less than that of the liquid.
3. The body will float inside the liquid if the density of the body is equal to that of the liquid.

Question 64.
If the relative density of a body is greater than 1, will it float in water?
Answer:
If the relative density of a body is greater than 1, it will not float in water.
[Note: The relative density of a pin is much greater than 1. But when kept gently on the surface of water, it floats. This is due to the surface tension of water.]

Question 65.
A glass of water has an ice cube floating in water. The water level must touches the rim of the glass. Will the water overflow when the ice melts? Give the reason.
Answer:
The water will not overflow when the ice melts. The water level will remain the same. Ice floats on water because its density is less than that of water. When ice melts, the volume of the water formed is less than the volume of the ice which has melted.

When ice in water melts, this difference equals the volume of the water formed when the part of ice above the surface of water melts. Therefore, the water level remains the same. Hence, there is no overflow of water when the ice melts.

Question 66.
A plastic ball is released underwater. State whether it will sink or come up to the surface of water. Give the reason.
Answer:
A plastic ball released under water will come up to the surface of water. The density of water is greater than that of plastic. Hence, when a plastic ball is under water, the magnitude of the buoyant force exerted by water on the ball is greater than the magnitude of the weight of the ball.

Therefore, the ball will start moving upward. As it comes up with part of the ball above the water surface, the volume of the water displaced by the ball becomes less and hence at a certain stage, the buoyant force and the weight balance each other. Then the ball continues to remain in that state, as the net force on the ball becomes zero.
[Note: Initially, the ball moves slightly up and down near the water surface. The force due to friction with water, opposing the motion of the ball, finally makes the ball steady.]

Write short notes:

Question 1.
Buoyant force.
Answer:
1. When a body is immersed partially or completely in a liquid, the liquid exerts forces on all sides of the body. This force is perpendicular to the surface of the body and equals the product of pressure and area at that point.

2. The resultant of all these forces acts upward. It is called the upthrust or buoyant force.

3. The buoyant force is proportional to (i) the volume of the liquid displaced by the body (ii) the density of the liquid (iii) the acceleration due to gravity. Its magnitude equals the magnitude of the weight of the liquid displaced by the body.

Question 2.
Applications of Archimedes’ principle.
Answer:
1. The working of a lactometer, a device used to determine the purity of a sample of milk, and a hydrometer, a device used to determine the density of a liquid, is based on Archimedes’ principle. The extent to which a lactometer floats (or sinks) depends on the density (and hence purity) of the milk. The same thing is true for a hydrometer. The greater the density of a liquid, the less is the extent to which a body sinks in it.

2. Archimedes’ principle is used in design of ships and submarines. A submarine is provided with large tanks at the front and the back. Its weight can be increased by filling the tanks with sea water or air from compressed air reservoirs. The weight can be decreased by pumping out water from the tanks by forcing compressed air in them. By controlling the weight, it can be made to sink or rise to the surface as desired.

3. The density of a body that floats or sinks in water or kerosine can be determined by. Archimedes’ principle.
4. The density of kerosine can be determined by Archimedes’ principle, using a body of material that is not affected by water and kerosine.

Give scientific reasons:

Question 1.
The tiles are placed over a slushy patch of ground to help cross It.
Answer:

1. Tiles have greater area than the area of our feet.
2. The weight of the person crossing the slushy patch is exerted over a large area of the tiles.
3. Therefore, there is a decrease in the pressure and hence the tiles do not sink much in the slushy patch of ground. This helps to cross the slushy patch of ground.

[Note: If there were no tiles, the feet will come in direct contact with the slushy ground. The area of the feet being less, the weight of the person will act over a smaller area. Therefore. there will be more pressure and hence the feet will sink into the slushy ground.]

Question 2.
Drawing pins have flattened heads.
Answer:

1. The head of a drawing pin is flattened and the other end is pointed.
2. When enough force is applied to the head of the pin, the pressure due to the force on the pointed end increases tremendously and the pin can be easily inserted in the drawing board.
3. When we press the flattened end, the force applied spreads over a larger area. This reduces the pressure of the reaction force acting on the thumb. Hence, the thumb is not injured.
4. If the head of the pin is sharp, then the pressure due to the force would be more and hence the pressure of the reaction force would also be more and the sharp end would prick the thumb causing injury.

Question 3.
An iron nail sinks in water but a ship made from iron floats on water.
Answer:
1. An iron nail sinks in water because its density is more than that of water.
2. A ship made from iron, due to the particular shape given to it, displaces a large amount of water so that the buoyant force acting on the ship due to water balances the weight of the ship. Hence, the ship floats on water.

Question 4.
A piece of iron sinks in water but floats on mercury.
Answer:
The density of iron is more than that of water but less than that of mercury. Hence, a piece of iron sinks in water but floats on mercury.

Question 5.
A sheet of metal that sinks in water can float if shaped like a pan.
Answer:

1. A sheet of metal sinks in water because its density is more than that of water.
2. If the sheet is shaped like a pan, it can displace a large amount of water such that the buoyant force on the pan due to water balances the weight of the pan. Hence, it can float on water.

Solve the following examples:

Problem 1.
(i) Calculate the pressure exerted by the wooden block when it is kept in the vertical position.
Given: The length of the wooden block is 80 cm, the breadth is 50 cm, the thickness is 20 cm and the weight is 500 N
(ii) Also calculate the pressure when the wooden block is kept in the horizontal position with its surface 80 cm × 50 cm touching the floor.

Solution:
Data: F = W = 500 N, l = 80 cm = 0.8 m, b = 50 cm = 0.5 m. h = 20 cm = 0.2 m
(i) A = bh = 0.5 m × 0.2 m = 0.1 m²

The pressure exerted in the vertical position of the block = 5000 N/m² or 5000 Pa.

(ii) A = lb = 0.8 m × 0.5 m = 0.4 m²

The pressure exerted in the horizontal position of the block = 1250 N/m² or 1250 Pa.

Problem 2.
Measure the length, breadth, height and mass of a rectangular tiffin box. Find the weight of the box and calculate the pressure in two different positions as in Ex. (1) above.
Solution:
Let l = 0.25 m, 6 = 0.1 m, h = 0.05 m, F = W= 0.5 N
(i) A = bh = 0.1 m × 0.05 m = 0.005 m²

(ii) A = lb = 0.25 m × 0.1 m = 0.025 m²

Problem 3.
A force of 1000 N is applied over an area 50 cm × 20 cm. Find the corresponding pressure.
Solution:
Data: F = 1000 N,
A = 50 cm × 20 cm = 0.5 m × 0.2 m = 0.1 m², pressure = ?

The pressure = 10 N/m².

Problem 4.
A metal block has thmensions 10 cm × 5 cm × 2 cm and the density of the metal is 8 × 10³ kg/m³. It is kept on a table with the face 10 cm × 5 cm in contact with the table. Find the force and pressure exerted by the block on the table. (g = 9.8 m/s²)
Solution :
Data : 1 = 10 cm, b = 5 cm,
h = 2 cm, p= 8 × 10 kg/m3, g = 9.8 m/s²,
A = lb = 10cm × 5cm = 50cm² = 50 × 104m²
= 5 × 10^-5m², force =?, pressure = ?
Volume of the block = lbh =
10 cm × 5 cm × 2 cm= 100 cm³
= 100 × 10^-6 m³ = 1 × 10^-4m³
Mass of the block = volume × density
(∵ density = mass/volume)
∴Mass of the block,
m = 1 × 10^-4 m³× 8 × 10³ kg/m³ = 0.8 kg
Weight of the block = mg = 0.8 kg × 9.8 m/s² = 7.84 N
∴ The force exerted by the block on the table = 7.84 N.
force 7.84 N

= 1.568 × 10³ N/m² or 1.568 × 10³ Pa
The pressure exerted by the block on the table = 1.568 × 10 N/m2 or 1.568 × 10³ Pa.

Problem 5.
A body of volume loo cm³ is immersed completely in water. Find the weight of the water displaced by the body. 1g = 9.8 m/s². p (water) = kg/m³]
Solution :
Data: V = 100 cm³ = 100 × 10^-6 m³
= 1 × 10 m³, p(water) = 10 kg/m³
g = 9.8 m/s², weight of the displaced water ?
Density = \(\frac{\text { mass }}{\text { volume }}\)
∴ Mass = volume × density
Volume of the water displaced by the body = l × 10^-4 m³
∴Mass of the water displaced,
m = l × 10^-4 m³ × 10 kg/m³ = 0.1 kg
∴Weight of the water displaced
= mg = 0.1 kg × 9.8 m/s² = 0.98 N.
The weight of the water displaced by the body = 0.98 N.

Problem 6.
A body of mass 200 g and volume 50 cm³ is put in a bucket containing water. Will it float or sink ?
[ρ(water) = 1 g/cm³]
Solution:
Data: m = 200 g, V= 50 cm³,
ρ (water) = 1 g/cm³
Density(ρ) = \(\frac{\text { mass }}{\text { volume }}\)
∴ ρ (body) = \(\frac{200}{50 \mathrm{~cm}^{3}}\)
It is greater than the density of water.
Hence, the body will sink in water.

Problem 7.
A body of mass 200 g and volume 400 cm³ is put in a bucket containing water. Will it float or sink?
[ρ (water)=1 g/cm³]
Solution:
Proceed as above.
ρ (body) = \(\frac{200 \mathrm{~g}}{400 \mathrm{~cm}^{3}}\) = 0.5 g/cm³
It is less than the density of water.
∴ The body will float in water.

Problem 8.
The mass of a tile is 500 g. If the density of the tile is 2.5 g/cm³, what will be the weight of the tile when it is completely immersed in water?
(g = 9.8 m/s², ρ(water) = 1000 kg/m³)
Solut10n:
Data: m = 500, g = 0.5 kg, ρ
(tile) = 2.5 g/cm³ = 2500 kg/m³, g = 9.8 m/s²,
ρ (water) = 1000 kg/m³, weight of the tile when completely immersed in water (also called the apparent weight) = ?
ρ = \(\frac{m}{V}\)

∴ Volume of water displaced by the tile
= 2 × 10^-4 m³
∴ Mass of water displaced by the tile
m’ = ρ (water) V = 1000 kg/m³ × 2 × 10^-4 m³
= 0.2kg
∴ Magnitude of the weight of this water
= mg = 0.2 kg × 9.8 m/s² = 1.96 N
∴ Buoyant force exerted on the tile = 1.96 N
Magnitude of the weight of the tile =
mg = 0.5 kg × 9.8 m/s² = 4.9 N
∴ Weight of the tile when completely immersed in water (apparent weight) = weight of the tile in air-buoyant force on the tile
= 4.9 N – 1.96 N = 2.94 N(downward)

Examples For Practice:

[g = 9.8 m/s², ρ (water) = 10³ kg/m³ = 1 g/cm³]

Question 1.
Calculate the relative density of a metal having density 7.5 g/cm³.
Answer:
7.5

Question 2.
Find the density of steel if its relative density is 8 and the density of water is 10 kg/m³.
Answer:
8 × 10³ g/cm³

Question 3.
A body has mass 200 g and volume 100 cm³. Find its density and relative density.
Answer:
2 g/cm³, 2

Question 4.
If the relative density of a material is 2.5, find its density.
Answer:
2.5 × kg/m³ or 2.5 g/cm³

Question 5.
A force of 100 N is applied on an area 40 cm × 25cm. Find the corresponding pressure.
Answer:
10³ N/m²

Question 6.
If the pressure exerted on an area 10 cm × 10 cm is 1000 dynes/cm², find the applied force.
Answer:
10⁵ dynes

Question 7.
A metal block of mass 10 kg is kept on a table. If the contact surface area Is 100 cm², find the pressure on the table.
Answer:
9.8 × 10³ N/m² or 9.8 × 10³ Pa

Question 8.
A body of volu.me 50 cm³ is immersed completely in water. Find the weight of the water displaced by the body.
Answer:
0.49 N

Question 9.
A block of mass 100 g and volume 20 cm³ is put in a bucket filled with water. Will it float or sink?
Answer:
The body will sink in water.

Question 10.
Will a block of mass 100g and volume 400 cm³ float or sink in water?
Answer:
The block will float in water.

Question 11.
The volume of a cube is 125 cm³ and its mass is 250 g. It is put in a tub containing water. Will it float or sink?
Answer:
It will sink in water.

Balbharti Maharashtra State Board Class 7 History Solutions Chapter 5 The Foundation of the Swaraj Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 7 History Solutions Chapter 5 The Foundation of the Swaraj

Class 7 History Chapter 5 The Foundation of the Swaraj Textbook Questions and Answers

1. Find the odd man out:

Question 1.
Pune, Supe, Chakan, Bengaluru
Answer:
Bengaluru

Question 2.
Jadhavs of Phaltan, Mores of Javali, Ghorpades of Mudhol, Sawants of Sawantwadi
Answer:
Jadhavs of Phaltan

Question 3.
Torana, Murumbdev, Sinhgad,Sindhudurg
Answer:
Sindhudurg.

2. Write about in your words:

Question 1.
The efforts Veermata Jijabai took for Shivaji Maharaj’s education.
Answer:
The following were the efforts Veermata Jijabai took for Shivaji Maharaj’s education.
(i) She instilled in Shivaji the values like modesty, vigilance, truthfulness, oratory, courage and fearlessness.
(ii) She inspired the will to win the dream of Swaraj.

Question 2.
Shivaji Maharaj started his work of founding Swaraj in the Maval region.
Answer:
(i) The Maval terrain was full of hills and valleys and was not easily accessible.
(ii) He made use of these geographical features of Maval very skilfully for the purpose of the foundation of the Swaraj.

3. List the companions and associates of Shivaji Maharaj.
Answer:

1. Yesaji Kank
2. Baji Pasalkar
3. Bapuji Mudgal
4. Kavji Kondhalkar
5. Jiva Mahala
6. Tanaji Malusare
7. Kanhoji Jedhe
8. Bajiprabhu Deshpande
9. Dadaji Narasprabhu Deshpande.
10. Narhekar Deshpande brothers

4. Find out and write:

Question 1.
Why Shahaji Maharaj is termed Swaraj visionary.
Answer: .
(i) Shahajiraje was valiant, courageous, intelligent a great political expert.
(ii) He was an excellent archer.
(iii) He was also an expert in using the sword, patta and spear.
(iv) He loved his subjects.
(v) He had won many regions in Maharashtra, Karnataka and Tamil Nadu. South India was in awe of him.
(vi) While Shivaji and Jijabai were at Bengaluru he had arranged for providing excellent education to Shivaji so as to enable him to become a king.
(vii) He himself aspired to established Swaraj by ousting the powers of foreign people. That is why he is known as Swaraj visionary.

Question 2.
Shivaji Maharaj paid attention to building a Navy.
Answer:
(i) After the conquest of Javali, Kalyan, Bhiwandi, Shivaji Maharaj came in contact with the Siddi, Portuguese and British power on the western Coast.
(ii) He realized that in order to fight these powers, it was necessary to have a strong naval force. Hence Shivaji Maharaj paid attention to raise a Navy.

Question 3.
Shivaji Maharaj entered into a treaty with the Adilshah.
Answer:
(i) On one hand, Aurangzeb had Sent Shaistakhan to invade the Pune Province and on other hand the conflict with Adilshah continued.
(ii) Therefore, Shivaji Maharaj realized that it would hot be prudent to fight both the enemies at the same time.
Therefore Shivaji Maharaj entered into a treaty with the Adilshah.

Question 4.
How did Shivaji Maharaj escape from Panhalgad?
Answer:
(i) When Shivaji Maharaj took shelter in Panhala fort, Siddi soldiers laid siege to the fort for about five months.
(ii) Shivaji Maharaj found himself trapped inside the fort.
(iii) Netoji Palkar tried to raise the siege by attacking Siddi’s army from outside.
(iv) He couldn’t succeed as his forces were meagre (inadequate)
(v) Siddi showed no sign of relenting so he decided to have open talks with him.
(vi) Shiva Kashid, a brave youth who resembled Shivaji Maharaj in looks came forward.
(vii) He dressed up like Shivaji Maharaj and sat in a palanquin.
(viii) The palanquin left by the Raj-dindi gate and was captured by Siddi’s army and Kashid sacrificed himself for Swaraj.
(ix) In the meanwhile, Shivaji Maharaj left the fort using another route.

Activities:

1. Describe a fort you have seen. Suggest measures for conserving a historical site.
2. Find out what a 7/12 extract means and relate it to the words in the chapter.

Class 7 History Chapter 5 The Foundation of the Swaraj Additional Important Questions and Answers

Complete the sentence by choosing the appropriate words from the options given below:

Question 1.
Shivaji Maharaj started the work of establishing Swaraj in the ______ region. (Maval, Javali, Chakan)
Answer:
Maval

Question 2.
Jijabai was the daughter of the great Sardar ______ (Shahajiraje, Netaji Palkar, Lakhujiraje)
Answer:
Lakhujiraje

Question 3.
______ was the first capital of Swaraj. (Pratapgad, Rajgad, Panhala)
Answer:
Rajgad

Question 4.
Shivaji Maharaj renamed Khelna as ______.(Vishalgad, Pratapgad, Rajgad)
Answer:
Vishalgad

Question 5.
The Adilshah gave Siddi the title of _____ (Salabatkhan, Adilshahi, Nizamshahi)
Answer:
Salabatkhan

Question 6.
Badi Sahiba sent ______ to curb Shivaji Maharaj. (Nizamshah, Afzalkhan, Shaistakhan)
Answer:
Afzalkhan

Question 7.
________ was a pre-eminent Sardar in the Deccan.(Lakhujiraje, Bajiprabhu Deshpande, Shahajiraje)
Answer:
Shahajiraje

Question 8.
The Nizamshahi came to an’end in _______. (1636 CE, 1648 CE, 1630 CE)
Answer:
1636 CE

Question 9.
Shahajiraje sent ______ and _______ from Bangalore to Pune with some loyal and competent associates. (Yesaji Rank and Jiva Mahala, Dalvi and Surve, Shivaji and Jijabai)
Answer:
Shivaji and Jijabai

Question 10.
Shivaji Maharaj took shelter in the _______ Fort. (Rajgad, Panhala, Vishalgad)
Answer:
Panhala

Match the following:

Question 1.

Column ‘A’	Column ‘B’
(1) Nizamshahi came to an end	(a) 1660 CE
(2) Shivaji’s birth date	(b) 10th November 1659
(3) A meeting between Shivaji and Afzalkhan	(c) 1636 CE
(4) Siddi Jauhar attacked on Shivaji Maharaj	(d) 19th February 1630.

Answer:
1 – c
2 – d
3 – b
4 – a

Question 2.

Column ‘A’	Column ‘B’
(1) Shivneri	(a) Javali Valley
(2) Pratapgad	(b) Siege by Siddi Jauhar
(3) Raigad	(c) Birth place of Shivaji Maharaj
(4) Panhalgad	(d) The first capital of the Swaraj

Answer:
1 – c
2 – a
3 – d
4 – b

Arrange in chronological order:

Question 1.
(i) A treaty with Adilshah
(ii) Defeat of Afzalkhan
(iii) Shivaji Maharaj captured Javali
(iv) Shivaji Maharaj escaped from Panhala Fort
Answer:
(i) Shivaji Maharaj captured Javali
(ii) Defeat of Afzalkhan
(iii) Shivaji Maharaj escaped from Panhala Fort
(iv) A treaty with Adilshah

Question 2.
(i) Meeting with Afzalkhan
(ii) End of Nizamshahi
(iii) Siege to Panhala
(iv) Attack on Javali
Answer:
(i) End of Nizamshahi (1636 CE)
(ii) Attack on Javali (1656 CE)
(iii) Meeting with Afzalkhan (1659 CE)
(iv) Siege to Panhala (1660 CE)

Question 3.
(i) Siddi Jauhar marched against Shivaji Maharaj
(ii) Birth of Shivaji Maharaj
(iii) Shivaji Maharaj built Pratapgad
(iv) Shahajiraje became a Sardar of Adilshah
Answer:
(i) Birth of Shivaji Maharaj
(ii) Shahajiraje became a Sardar of Adilshah
(iii) Shivaji Maharaj built Pratapgad
(iv) Siddi Jauhar marched against Shivaji Maharaj

Answer the following in one sentence:

Question 1.
What were the extraordinary qualities of Shahajiraje.
Answer:
Shahajiraje was a valiant, courageous, intelligent and a great political leader.

Question 2.
Which Jagirs were granted to Shahajiraje from Nizamshah?
Answer:
Shahajiraje was granted the jagirs of Pune, Supe, Indapur and Chakan parganas located between the Bheema and Neera rivers.

Question 3.
Who was Afzalkhan?
Answer:
Afzalkhan was a powerful and experienced Adilshahi General.

Question 4.
Which forts did Shivaji Maharaj capture while laying the foundation of Swaraj?
Answer:
Shivaji Maharaj captured the forts of Torana, Murumbdev, Kondhana and Purandar while laying the foundation of Swaraj.

Question 5.
Whom did Shahajiraje entrust the jagir of Pune?
Answer:
Shahajiraje entrusted the jagir of Pune to Shivajiraje and Veermata Jijabai.

Question 6.
Who was looking after the administration of the Adilshahi?
Answer:
Badi Sahiba was looking after the administration of the Adilshahi.

Question 7.
Whom did Badi Sahiba send to curb Shivaji Maharaj?
Answer:
Badi Sahiba sent Afzalkhan, a powerful and experienced Adilshahi General to curb Shivaji Maharaj.

Question 8.
What is inscribed on the Royal Seal?
Answer:
Shivaji Maharaja’s objective of establishing Swaraj was clearly expressed in his Royal Seal.

Question 9.
Who was Chandrarao More?
Answer:
Chandrarao More of Javali in Satara district was a powerful Sardar in the Adilshahi, who was against the founding of the Swaraj.

Question 10.
When was Shivaji Maharaj bom?
Answer:
Shivaji Maharaj was bom on 19th February, 1630 and as per Hindu Calendar on Phagun Vadya Tritiya, Shaka year 1551.

Find the odd man out:

Question 1.
Yesaji Kank, Baji Pasalkar, Tanaji Malusare the Mores of Javali
Answer:
The Mores of Javali.

Question 2.
Portuguese, Siddi, British, Mughals
Answer:
Mughals

Give reasons for the following:

Question 1.
Shivaji Maharaj decided to acquire the forts that were within his own jagir.
Answer:

• The forts situated within the jagir of Shivaji Maharaj were not under his control but were under the control of Adilshah.
• In those days, forts were of special significance.
• With a firm hold over a fort, it was possible to control the surrounding area. Hence, Shivaji Maharaj decided to acquire the forts that were within his own jagir.

Question 2.
Conquest of Javali increased Shivaji Maharaj strength in all respects.
Answer:

• Shivaji Maharaj attacked Javali and captured the region in 1656 CE.
• Shivaji Maharaj established his post in Javali.
• He also captured Raigad. He attained a huge wealth from Javali.
• After this victory, his activities in Konkan increased.
• He built the Pratapgad fort in the Javali valley.
• In this way, the conquest of Javali increased his strength in all respects.

Question 3.
Bajiprabhu dies a hero’s death.
Answer:

• Shivaji Maharaj left the fort using another difficult route.
• He was accompanied by Bajiprabhu Deshpande and some chosen soldiers.
• Bajiprabhu army pursued Shivaji Maharaj.
• Shivaji Maharaj entrusted the responsibility of stopping Siddi’s army at the foot of Vishalgad to Bajiprabhu Deshpande.
• Bajiprabhu Deshpande checked Siddi’s army at the Ghod pass near Gajapur.
• He fought with the greatest valour.
• Bajiprabhu died a hero’s death in the battle.

Find out and write:

Question 1.
Adilshah sent Siddi Jauhar, the Sardar of the Kamul region against Shivaji Maharaj in 1600 CE.
Answer:

• Shivaji Maharaj captured the Adilshahi forts of Panhala, Vasantgad and Khelna.
• Shivaji Maharaj had posed a big challenge before the Adilshahi.
• Therefore, Adilshah sent Siddi Jauhar, the Sardar of the Kamul region against Shivaji Maharaj in 1660 CE.

Write in short about:

Question 1.
Defeat of Afzalkhan
Answer:

• Badi Sahiba sent the powerful and experienced Afzalkhan to curb Shivaji Maharaj.
• A meeting between Afzalkhan and Shivaji was arranged at the foot of Pratapgad near Wai.
• At the meeting, Afzalkhan attempted treachery.
• In return, Shivaji Maharaj killed Afzalkhan and routed the Adilshahi army.

Question 2.
Royal Seal (Rajmudra)
Answer:

• The objective of Shivaji Maharaj of establishing of Swaraj is expressed in his Royal Seal.
• The meaning expressed is that this seal will grow in splendour like the new moon. The seal of Shivaji, the son of Shivaji receiving homage from the whole world denotes the welfare of the people.

Question 3.
Veermata Jijabai
Answer:

• Jijabai was daughter of the great Sardar Lakhujiraje Jadhav of Sindkhedraja in Buldhana district.
• At a young age, she had received military education along with learning various arts.
• She helped and encouraged Shahaji Maharaj to realise his dream of establishing Swaraj
• She was a competent and visionary political expert.

Let’s Learn:

Observe the official seal of our country.

Question 1.
What features do you observe?
Answer:

• Official seal is called the National Emblem of India.
• Elephant is in East, Horse in west (left), Bull south (right) and lion in North.
• There are four lions standings back to back, but in the emblem three are seen.
• There is a wheel under the lions.
• Underneath there are the words “Satyameva Jayate’ in Devnagri script.

Question 2.
In which places is the official seal used?
Answer:
Coins, currency notes, postcards, envelops, passport and Government documents.