Question 1.
What are the three main factors that determine the outcome of social divisions in politics? Explain. (2014, 2013)
Answer:
Three factors determining the outcome of social divisions in politics are:
(i) How people perceive their identities. If people see their identities in exclusive terms, it becomes difficult to accommodate them. As long as people in Northern Ireland saw themselves as only Catholic or Protestant, their differences were difficult to reconcile. It is easier if identities are complementary with national identities. This helps to stay together. This is how most people in our country see their identity. They feel and think as Indian as well as belonging to a State or a language group or a social or religious group.

(ii) How political leaders raise demands of any community. It is easier to accommodate demands that are within the constitutional framework and are not at the cost of another community. The demand for ‘only Sinhala’ was at the cost of the interest and identity of the Tamil community in Sri Lanka.

(iii) How Government reacts to demands of different groups. If the rulers are willing to share power and accommodate the reasonable demands of minority community, as in Belgium, social divisions become less threatening for the country. But if the demand is suppressed in the name of national unity, as in Sri Lanka, the end result is quite opposite. Such attempts at forced integration sow the seeds of disintegration.

Question 2.
Why do some people think that it’s not correct to politicize social divisions? Give three reasons. 2014
Answer:
Social divisions of one kind or another exist in most countries of the world and these divisions are reflected in politics and affect politics. Expression of social divisions in politics lead to disaster. If social divisions do exist in a country, they must never be expressed in politics, because the combination of politics and social divisions is very dangerous.

• Democracy involves competition among various political parties. Their competition tends to divide society.
• If they start competing in terms of some existing social division, it can make social divisions into political divisions and lead to conflict, violence or even disintegration of a country. In Yugoslavia, political competition along religious and ethnic lines led to disintegration of the country into six independent countries.
• Social divisions affect voting in most countries. People from one community tend to prefer some party more than others.

Question 3.
“In a democracy, political expression of social division is very normal and can be healthy”. Justify this statement with suitable arguments. (2015)
Answer:
In a democracy, political expression of social divisions is very normal and can be healthy. This allows various disadvantaged and marginal social groups to express their grievances and get the government to attend to these.

Taking the examples of Belgium and Sri Lanka, if the rulers are willing to share power and accommodate the reasonable demands of minority community, social divisions become less threatening for the country. In fact it may prove healthy for a democracy.

Expressions of various kinds of social divisions in politics often results in their cancelling one another and thus reducing their intensity. This leads to strengthening of democracy.

As long as people in northern Ireland saw themselves as only Catholic or Protestant, their differences were difficult to reconcile.

A majority of Belgians now feel that they are as much Belgian as they are Dutch or German-speaking. This helps them to stay together.

Question 4.
Explain the two bases of Social differences with examples. 2017D
Answer: Origins of Social differences:

1. Accident of birth. We don’t choose to belong to our community. We belong to it simply because we were born into it. We experience social differences based on accident of birth in our everyday lives
2. Based on choices. Some of the differences are based on our choices. Some people are atheists. They don’t believe in God or any religion. Some people choose to follow a religion other than the one in which they were born. Most of us choose to study a subject of our interest and an occupation where we can excel. All these lead to formation of social groups that are based on our choices.

Question 5.
What penalty was imposed on ‘Carlos, Smith and Norman’ for their action at the 1967 Mexico Olympics? (2017 OD)
Answer:

1. The International Olympic Association held Carlos and Smith guilty of violating the Olympic spirit by making a political statement. Their medals were taken back.
2. In America, they were subjected to a lot of criticism.
3. Norman was excluded from the Australian team in the next Olympics.

Question 6.
What are the three main factors that determine the outcome of social divisions in politics? Explain.
Answer:
Three factors determining the outcome of social divisions in politics are:
(i) How people perceive their identities. If people see their identities in exclusive terms, it becomes difficult to accommodate them. As long as people in Northern Ireland saw themselves as only Catholic or Protestant, their differences were difficult to reconcile. It is easier if identities are complementary with national identities. This helps to stay together. This is how most people in our country see their identity. They feel and think as Indian as well as belonging to a State or a language group or a social or religious group.

(ii) How political leaders raise demands of any community. It is easier to accommodate demands that are within the constitutional framework and are not at the cost of another community. The demand for ‘only Sinhala’ was at the cost of the interest and identity of the Tamil community in Sri Lanka.

(iii) How Government reacts to demands of different groups. If the rulers are willing to share power and accommodate the reasonable demands of minority community, as in Belgium, social divisions become less threatening for the country. But if the demand is suppressed in the name of national unity, as in Sri Lanka, the end result is quite opposite. Such attempts at forced integration sow the seeds of disintegration.

Question 7.
Distinguish between overlapping and cross-cutting of social differences. (2013)
Answer:
Difference between Overlapping and Cross-cutting of social

Question 9.
Explain the origins of social differences. (2014, 2013)
Answer:
Origins of Social differences:

1. Accident of birth. We don’t choose to belong to our community. We belong to it simply because we were born into it. We experience social differences based on accident of birth in our everyday lives.
2. Based on choices. Some of the differences are based on our choices. Some people are atheists. They don’t believe in God or any religion. Some people choose to follow a religion other than the one in which they were born. Most of us choose to study a subject of our interest and an occupation where we can excel. All these lead to formation of social groups that are based on our choices.
   For example, Nagaland, Uttrakhand and Jharkhand.
3. Restricting of Centre-State relations. The constitutional arrangements for sharing power work depending on how the ruling parties and leaders follow these arrangements. For a long time, the . same party ruled both at the Centre and in most of states. Post-1990 saw the rise of regional parties. Since no single party got a clear majority in the Lok Sabha, the national parties had to enter into an alliance which led to a new culture of power sharing and respect for autonomy of State Governments

Question 10.
“Assertion of social diversities need not be seen as a source of danger”. Explain the statement with three arguments. (2013)
Answer:

• In a democracy, political expression of social divisions is very normal and can be healthy. This allows various disadvantaged and marginal social groups to express their grievances and get the government to attend to these.
• Expression of various kinds of social divisions in politics often results in their cancelling one another out and thus reducing their intensity. This leads to strengthening of a democracy.
• But a positive attitude towards diversity and a willingness to accommodate it do not come about easily. People who feel deprived have to fight against the injustices. Such a fight often takes the democratic path, voicing their demands in a peaceful and constitutional manner.

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Question 1.
Why is decentralisation favoured in democracy? Identify any two reasons. (2014)
Answer:
Five advantages of decentralisation of power:

1. When power is taken away from Central and State Governments and given to local governments, it is called decentralisation. The basic idea behind decentralisation is that there are a large number of problems and issues which are best settled at the local level. People have better knowledge of problems in their localities.
2. They also have better ideas on where to spend money and how to manage things more efficiently.
3. Besides, at the local level, it is possible for the people to directly participate in decision making. This helps to inculcate a habit of democratic participation.
4. Local government is the best way to realise one important principle of democracy, namely local self¬government.
5. The need for decentralisation was recognised in our Constitution. A major step towards decentralisation was taken in 1992. The Constitution was amended to make the third tier of democracy more powerful and effective.

Question 2.
India comes under which type of federation and why? (2014)
Answer:
India comes under ‘a holding together’ type federation. In this type of federation, a large country divides its power between the constituent States and the National government. There is one government for the entire country and the others are governments at the State level. Both Central and State Governments enjoy their power independent of the other.

The Central government tends to be more powerful vis-a-vis the states. Often different constituent units of the federation have unequal powers. For example, special powers have been granted to Jammu & Kashmir.

Question 3.
State two agreements through which federations have been formed. Give an example of each.
Answer:
(i) ‘Coming together’ federations—This agreement induces independent states coming together on their own to form a bigger unit, so that by pooling sovereignty and retaining identity they can increase their security.
Examples are: USA, Switzerland and Australia. All the constituent states have equal power and are strong vis-a-vis the federal government.

(ii) ‘Holding together’ federations — In this agreement, a large country decides to divide its power between the constituent States and the national government. The Central Governments tend to be more powerful vis-a-vis the states. Often different constituent units of the federation have unequal powers. Some units are granted special powers, for example, India granted special powers to Jammu & Kashmir.
Other examples are Spain and Belgium.

Long Answer Questions (LA)

Question 4.
Which five provisions of the constitutional amendment of 1992 really strengthened the third tier of democracy in India? Explain. (2015, 2013, 2012)
Answer:
Major steps towards decentralisation and strengthening of third tier taken in 1992 were:

1. Now it is constitutionally mandatory to hold regular elections to Local Government bodies.
2. Seats are reserved in elected bodies for scheduled castes, scheduled tribes and other backward classes (OBCs).
3. Atleast one-third of all positions and seats are reserved for women.
4. An independent institution called the State Election Commission was created to conduct Panchayat and Municipal elections.
5. The State Governments are required to share some powers and revenue with Local Government bodies.

Question 5.
Why has federalism succeeded in India? Which are the policies adopted by India that have ensured it? Explain. (2013, 2012)
Answer:
Reasons for success of federalism in India are:

1. Clearly laid out Constitutional Provisions providing a three-fold distribution of powers in the three lists—Union List, State List and Concurrent List—between the Union Government and State Governments.
2. The nature of democratic politics in our country which ensures that the spirit of federalism, respect for diversity and desire for living together became a shared ideal.
3. The creation of linguistic states. Boundaries of several old states of India were changed in order to create new states. This was done to ensure that people who spoke the same language lived in the same state. Later some states were created to recognise differences based on culture, ethnicity or geography.
   For example: Nagaland, Uttrakhand, Jharkhand, Telangana, etc.
4. Restricting Centre-State relations. The constitutional arrangements for sharing power work depending on how the ruling parties and leaders follow these arrangements. For a long time, the same party ruled both at the Centre and in most of states. Post-1990 saw the rise of regional parties. Since no single party got a clear majority in the Lok Sabha, the national parties had to enter into an alliance which led to a new culture of power sharing and respect for autonomy of State Governments.

Question 6.
Explain any five features of federalism. (2015)
Answer:
Features of federalism:

1. There are two or more levels of government.
2. Different levels of government govern the same citizens, where each level has its own jurisdiction in specific matters of legislation, taxation and administration.
3. Existence and authority of each level of government is constitutionally governed.
4. The fundamental provisions of the Constitution cannot be unilaterally changed. Such changes require the consent of both the levels of government.
5. Courts have the power to interpret the Constitution and powers of the different levels of government. The highest court acts as the umpire if any dispute arises between different levels of governments.
6. Sources of revenue for each level of government are specified to ensure its financial autonomy.
7. Federal system has dual objectives. To safeguard and promote unity of the country, and to accommodate regional diversity.

Question 7.
Describe the three forms of power sharing among different organs of government in India. (2014)
Answer:
The Constitution declared India as a Union of States based on the principles of federalism. The Constitution originally provided for a two-tier system of government, the Union or the Central Government representing Union of India and the State Governments. Later, a third tier was added in the form of Panchayats and Municipalities.

As in any federation, these different tiers enjoyed separate jurisdiction. The Constitution provided a three-fold distribution of legislative powers:

1. Union List includes subjects of national importance, i.e., defence of the country, foreign affairs, banking, communications and currency.
2. State List contains subjects of state and local importance, i.e., police, trade, commerce, agriculture and irrigation.
3. Concurrent List includes subjects of common interest to both the Union Government as well as the State Governments, i.e., education, forests, trade unions, marriages, adoption and succession.
   In case of dispute, law made by the Union Government shall prevail.
4. Residuary—Subjects which do not fall in any of the three lists, i.e., computer software, etc. Union Government has the power to legislate such subjects.
   • As India is an example of ‘holding together’ federation, all states in the Indian Union do not have identical powers. Some states enjoy special status such as Jammu & Kashmir. There are some states too small to become independent like the Union Territories of Chandigarh and Lakshadweep.
   • This sharing of power between the Union Government and State Governments is basic to the structure of the Constitution. Any change to it, has to be passed by both the Houses of the Parliament with at least two-third majority.
   • The judiciary plays an important role in the implementation of constitutional procedures. In case of any dispute about division of powers, the High Courts and the Supreme Court make a decision.

Question 8.
Describe in brief the language policy of India?
Answer:

1. Our Constitution did not give the status of national language to any one language.
2. The formation of linguistic states united the country and made administration easier.
3. The leaders of our country adopted a very cautious attitude in spreading the use of Hindi. Hindi was identified as official language.
4. The banning of use of English for official purposes in 1965 took a violent form in Tamil Nadu. The Central Government responded by agreeing to continue the use of English along with Hindi for official purposes.
5. Promotion of Hindi is an official policy of the Government of India but it does not impose Hindi on states where people speak a different language.
6. Besides Hindi, there are 21 other languages recognised as scheduled languages by the Constitution.
7. This flexibility shown by Indian leaders helped our country avoid the situation that Sri Lanka finds itself in.

Question 9.
What were the major steps taken to make decentralisation more effective?
Or
What amendments were made in the Constitution in order to make the third tier of democracy (Local Government) more powerful and effective?
Answer:
Major steps towards decentralisation taken in 1992 are:

1. Now it is constitutionally mandatory to hold regular elections to Local Government bodies.
2. Seats are reserved in elected bodies for scheduled castes, scheduled tribes and other backward classes (OBCs).
3. Atleast one-third of all positions are reserved for women.
4. The State Election Commission was created to conduct Panchayat and Municipal elections.
5. The State Governments are required to share some powers and revenue with Local Government bodies.

Question 10.
Explain the structure of the new Panchayati Raj institutions, both in rural and urban areas.
Answer:
Rural Local Government is known by the name of Panachayati Raj/ Democratic decentralization.

• Each village or group of villages has a Gram Panchayat.
• Panch, President or Sarpanch are directly elected by all the adult population of the village and is the decision-making body.
• The Panchayat works under the supervision of Gram Sabha, with all the voters as its members.
• The local structure goes up to the district level—a group of Gram Panchayats form a Panchayat Samiti or Block or Mandal.
• All the Panchayat Samitis or Mandals together constitute the Zilla Parishad which consists of elected members.
• Lok Sabha members, Local MLAs and officers are also members of the Zilla Parishad.
• Its Chairperson is the political head of the Parishad.

Urban areas local bodies.

• Municipalities are set up in towns.
• Big cities are constituted into Municipal Corporations.
• Both are controlled by elected bodies consisting of people’s representatives.
• Municipal chairperson is the political head of the Municipality.
  The head of Municipal Corporation is an officer called the Mayor.

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Question 1.
How far do you agree with the statement that power sharing is keeping with the spirit of democracy? (2012)
Answer:
Power sharing is desirable in democracy because it helps to reduce the possibility of conflict between social groups. Conflict between social groups leads to violence and political instability. Power sharing is a good way to ensure the stability of political order.

Imposing the will of majority community over others, in the long run may undermine the unity of the nation. Tyranny of the majority is not just oppressive for the minority, it often brings ruin to the majority as well.

A democratic rule involves sharing power with those affected by its exercise and who have to live with its effects. People have a right to be consulted on how they are to be governed. A legitimate government is one where citizens, through participation, acquire a stake in the system. Prudential reasons stress that power sharing brings out better outcomes whereas moral reasons emphasize the act of power sharing as valuable.

Question 2.
Explain any three consequences of the majoritarian policies adopted by the Sri Lankan government. (2013)
Answer:
Sri Lanka emerged as an independent country in 1948. The democratically elected government adopted a series of majoritarian measures to establish Sinhala Supremacy. Consequences of these majoritarian policies:

1. The Sri Lankan Tamils felt that none of the major political parties led by the Buddhist Sinhala leaders were sensitive to their language and culture and the government policies denied them equal political rights which led to increased feeling of alienation among them.
2. The Sri Lankan Tamils felt that the constitution denied them equal rights in politics, in getting jobs and ignored their interests. The relation between the Tamil and Sinhala communities became extremely strained as a result.
3. The Sri Lankan Tamils launched parties and struggles for the recognition of Tamil, for regional autonomy and equality of opportunity in every field.
4. Therefore, the measures adopted by the government to establish Sinhala supremacy led to distrust between the two communities which turned the widespread conflict into a Civil War. As a result, thousands of people of both communities were killed and many families were forced to leave the country as refugees and lost their livelihoods.

Question 3.
Why is the ethnic composition of Belgium complex?
Answer:
Belgium is a small country in Europe, having a population of a little over one crore.

• 59 per cent of the country’s total population lives in the Flemish region and speak Dutch language.
• Another 40 per cent people live in Wallonia region and speak French. Remaining one per cent of the Belgians speak German.
• Whereas in the Belgian capital, Brussels, 80 per cent of the population is French-speaking and 20 per cent is Dutch-speaking.

Question 4.
How is Belgium’s power-sharing path different from any other country?
Or, Explain the four elements in the Belgian power-sharing model.
Or, Why do we find the Belgian model very complicated? How has it helped to prevent conflict and division of the country on linguistic lines?
Answer:
The power-sharing arrangements made by the Belgian leaders were different and more innovative than any other country. To recognise the existence of regional differences and cultural diversities, they amended their Constitution four times between 1970 and 1993.
The major elements of the Belgian Model are:

1. Constitution prescribes that the number of Dutch and French-speaking ministers shall be equal in the Central Government. No single community can take decisions unilaterally.
2. The State Governments are not subordinate to the Central Government.
3. Brussels, the capital, has a separate government where both the communities have equal representation.
4. A third kind of government, ‘Community Government’, is elected by people belonging to one language community — Dutch, French and German speaking —no matter where they live. This government can decide on cultural, educational and language related issues.

Question 5.
What is majoritarianism? Is it wrong if a majority community in a country rules? Give reasons to justify your answer.
Answer:
A belief that the majority community should be able to rule a country in whichever way it wants, by disregarding the wishes and needs of the minority is majoritarianism.
Yes, it is wrong if a majority community in a country rules.

• The very idea of power-sharing has emerged in opposition to the notions of undivided political power.
• A positive attitude towards diversity and willingness to accommodate it, is good for democracy.
• Power in the hands of one community will make the other community feel marginalised, deprived and discriminated.
• The struggle against such inequalities sometimes takes the path of conflict and defiance of State power as in Sri Lanka.

Question 6.
Analyse how majoritarianism has increased the feeling of alienation among the Sri Lankan Tamils? (2014, 2015)
Or
Mention the measures adopted by the government to establish Sinhala supremacy.
Sri Lanka emerged as an independent country in 1948. The democratically elected government adopted a series of measures to establish Sinhala supremacy:

1. In 1956, an Act was passed to make Sinhala the official language.
2. The government followed preferential policies favouring Sinhala applicants for University positions and government jobs.
3. The Constitution provided for State protection and fostering of Buddhism.

The Sri Lankan Tamils felt that none of the major political parties led by the Buddhist Sinhala leaders were sensitive to their language and culture and the government policies denied them equal political rights which led to increased feeling of alienation among them.

The Sri Lankan Tamils launched parties and struggles for the recognition of Tamil, for regional autonomy and equality of opportunity in every field.

Therefore, the measures adopted by the government to establish Sinhala supremacy led to distrust between the two communities which turned the widespread conflict into a Civil War.

Question 7.
“Power Sharing is the very spirit of democracy”. Justify the statement. (2015)
Answer:

1. A democratic rule involves sharing power with those affected by its exercise. Power sharing ensures that people have the right to be consulted and have equal participation in the government.
2. In a democracy, each individual has a say in governance through their elected representatives. This is the essence of power sharing that grants equal rights to each citizen.
3. Sharing of power ensures that respect for diversity and desire for living together becomes a shared ideal amongst different communities in a country. It actually makes the country united and the administration easier.
4. Prudential reasons stress that power sharing would bring out better outcomes by helping to reduce the possibility of any conflict between the social groups.
5. Power sharing is a good way to ensure the stability of political order through unity of the nation.

Question 8.
Describe the vertical and horizontal forms of power sharing exercised in India.
Answer:
Vertical distribution of power. Power can be shared among governments at different levels —a general government for the entire country and governments at provincial or regional level. This is the federal form of government.

When power is shared among governments at different levels, i.e., the Union or the Central Government, the State Government and the Municipality and Panchayat at the lower level. This division of power involving higher and lower levels of government is called the vertical division of power.

The Constitution clearly lays down the powers of different levels of government. This federal division of power involving higher and lower levels of government is also called the vertical division of power. Example: A key change in the Constitution of Belgium in 1993 was that the regional governments were given constitutional powers that were no longer dependent on the Central Government. Thus, Belgium shifted from a unitary to a federal form of government.

Horizontal distribution of power. Power is shared among different organs of government, such as the legislature, executive and judiciary. This is horizontal distribution of power. It ensures that power is shared among different organs of government—the legislature, executive and judiciary. It allows different organs of government placed at the same level to exercise different powers.

In a democracy, ministers and government officials exercise power. They are responsible to the Parliament or State Assemblies. The judges appointed by the executive can check the functioning of executive or laws made by the legislature.

The horizontal distribution of power is also called a system of checks and balances.

This system ensures that none of the organs can exercise unlimited power. Each organ checks the other. This results in a balance of power among various institutions.

Example: In India the judiciary has an independent status. The Supreme Court is the apex court of justice. The Parliament is the legislative body where the laws governing the country are made and the Executive is the implementing body.

Question 9.
What is vertical division of power?
Answer:
When power is shared among governments at different levels, i.e., the Union or the Central Government, the State Government and the Municipality and Panchayat at the lower level. This division of power involving higher and lower levels of government is called the vertical division of power.

Question 10.
Compare the different ways in which the Belgians and the Sri Lankans have dealt with the problem of cultural diversity. (2012)
Answer:
Both Belgium and Sri Lanka are democracies, yet they have dealt with the problem of cultural diversity very differently.
Belgium:

1. Leaders realised that for the unity of the country it is important to respect the feelings and interests of different communities. The Constitution prescribes that the number of Dutch and French speaking people shall be equal in the Central Government.
2. Both Dutch and French communities share power on an equal basis at the Centre. Along with the State Government, both communities have a third kind of Government called ‘Community Government’ which decides on cultural, education and language related issues.
3. Between, 1970 and 1993, the Constitution was amended four times to enable all linguistic groups to live together within the same country.

Sri Lanka:

1. In Sri Lanka, there are two major communities, the Sinhalese speaking (74%) and Tamil speaking (18%). The majority community, the Sinhalese have forced their domination over Tamils, refusing to share power.
2. Both communities have lived in tension as the Sinhalese have denied political, educational, religious, employment and economic rights to the Tamils leading to Civil War.
3. In 1956, the Government passed an Act to recognise Sinhala as the only official language, thus disregarding Tamil.

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1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi]
   Answer.
   

2. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India]
Answer.

3. Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed:
(i) at the centre of curvature of a concave mirror
(ii) between the pole P and focus F of a concave mirror
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a concave lens
Answer.

Nature of image: Real, inverted and same size image is formed at the centre of curvature.

Nature of image: Virtual, enlarged and erect image is formed behind the mirror.

Nature of image: Virtual, erect and diminished, image is formed behind the mirror.

Nature of image: Real, inverted and size to size, image is formed at 2F on the other side of lens.

Nature of image: Virtual, erect and diminished image is formed between O and F on the same side of object.

4. If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray. [Delhi (C)]

Answer. Ray NQ, as it has to be parallel to ray OS.

5. The refractive indices of four media A, B, C and D are given in the following table:

If light, travels from one medium to another, in which case the change in speed will be (i) minimum, (ii) maximum? [Delhi(C)]
Answer. (i) Minimum change is seen as light moves between 1.50 and 1.52, i.e. B and C.
(ii) Maximum change when light moves between 1.33 and 2.40, i.e. A and D.

6. “The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of light? [Delhi]
Answer.

7. Redraw the given diagram and show the path of the refracted ray: [All India(C)]

Answer.

8. Redraw the given diagram and show the path of the refracted ray: [All India(C)]

Answer.

9. Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed:
(a) at 2F₁
(b) between F₁ and the optical centre O of lens: [All India]
Answer.

10 .An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the image formed? Draw a ray diagram to show the formation of the image in this case. [Delhi(C)]
Answer.

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Question 1. List four advantages of water stored in the ground. [Delhi]
Answer. Four advantages of storing water in the ground are:

1.  It does not evaporate.
2. It is relatively protected from contamination by human and animal wastes.
3. It does not provide breeding ground for mosquitoes.
4. It provides moisture for vegetation.

Question 2. “Burning fossil fuels is a cause of global warming.” Justify this statement. [Delhi]
Answer. Fossil fuels like coal and petroleum are formed from biomass. In addition to carbon, they contain hydrogen, nitrogen and sulphur. When fossil fuels are burnt, the products are carbon dioxide, water vapour, oxides of nitrogen and oxides of sulphur. Carbon dioxide is a greenhouse gas. Increase in the percentage of carbon dioxide increases the temperature on earth which leads to global warming.

Question 3 List three problems which arise due to construction of big dams. Suggest a solution for these problems. [All India]
Answer. Three problems of construction of large dams are:

1. Displacement of large number of people.
2. Huge cost of construction and low benefit compared to cost.
   These problem can be sorted out by constructing smaller dams instead of a big dam.

Question 4. List the products of combustion of fossil fuels. What are their adverse effects on the environment? [All India]
Answer. When fossil fuels are burnt, carbon dioxide, water, oxides of nitrogen and oxides of sulphur are formed. If the combustion takes place in insufficient air, then carbon monoxide is formed instead of carbon dioxide. Of these products, the oxides of sulphur and nitrogen and carbon monoxide are poisonous gases and carbon dioxide is a greenhouse gas.

Question 5. State the meaning of “sustainable management”. Reuse is better than recycling. How? [Foreign]
Answer. ‘Sustainable management’ is the management of resources in which development can be maintained for a long time without undue damage to the environment.
Recycling needs additional energy to make a usable item. Reuse does not require additional energy and hence, is better than recycle.

Question 6 Why are forests considered “biodiversity hot spots”? List two ways in which an individual can effectively contribute to the management of forests and wildlife. [Foreign; All India 2010]
Answer. Biodiversity is measured by the number of different life forms found in an area. In a forest, various species exist which include bacteria, fungi, ferns, plants, nematodes, insects, birds, reptiles and mammals. Forests are therefore considered as biodiversity hot spots.
An individual can contribute in the management of forests and wildlife by:

1. avoiding cutting down of forests and killing of wildlife.
2. educating people about the importance of forests and wildlife in our life.

Question 7. How did ‘Chipko Andolan’ ultimately benefit the local people? Describe briefly. [Foreign]
Answer. Chipko Movement:

• During 1970, in Reni village of Garhwal, a contractor was allowed to cut trees in a forest near the village.
• When the contractor’s workers went to the forest to cut trees, the women of the village hugged the tree trunks to prevent the workers from cutting trees.
• Chipko means ‘hug’ and the movement began with the villagers hugging trees. It is called the ‘Chipko Andolan’.

The movement benefited the local population as it conserved the forest products. It benefited the environment as it conserved the quality of soil and sources of water thereby, maintained balance in nature.

Question 8. Which of the two is a better option, (i) to collect rainwater in ponds or artificial lakes, or (ii) to let it recharge groundwater by water harvesting? List two advantages of the option to justify your answer. [Foreign]
Answer. To allow rainwater to recharge groundwater by water harvesting is the better option. Its advantages are:
(i) Groundwater does not evaporate.
(ii) Groundwater does not provide breeding ground for mosquitoes.

Question 9 What is a dam? Write two main advantages and two ill-effects of constructing a big dam. [Delhi(C)]
Answer. Dams are massive barriers built across rivers and streams to confine and utilise the flow of water for human purposes such as irrigation and generation of electricity.
Two main advantages of constructing a big dam are:

1. Generation of electricity.
2. Irrigation.

Two ill-effects of constructing a big dam are:

1. It displaces large number of people.
2. It causes deforestation and loss of biodiversity.

Question 10. What is meant by sustainable management? The environmentalists are insisting upon “sustainable natural resource management”. State its four advantages. [All India (C)]
Answer. Sustainable management is the management of natural resources which requires a long-term perspective so that they last for generations to come and are not to be exploited by the short-term gains.
Its four advantages are as follows:

1. Resources last for a longer duration.
2. It provides steady economic growth.
3. It helps in ecological conservation.
4. It reduces pollution.

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1.(i) Name the hormones that are released in human males and females when they reach puberty.
(ii) Name a gland associated with brain. Which problem is caused due to the deficiency of the hormone released by this gland ?
Answer.
(i) Testes in males produces hormone testosterone.
Ovaries in females produces hormone oestrogen.
(ii)Pituitary gland present in the brain is responsible for body growth, development of bones and muscles (if excess-gigantism) (if less-dwarfism).

2. List in tabular form three differences between nervous control and chemical control.
Answer.

3.(a) Explain any three directional movements in plants.
(b) How brain and spinal cord are protected in human ?
(c) Name the master gland present in the brain.
Answer.
(a) Stimuli is responsible for the movement of the plant parts towards or away from it. This movement is called as Tropic Movement.
Phototropism: movement of plant towards or away from the light. Geotropism: movement of plant parts towards the earth or away from it. Hydrotropism: movement of plant parts towards or away from any source of water.
(b) Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull and the spinal cord is protected by a set of ring-shaped bones called vertebrae. They are both cushioned by layers of membranes called meninges as well as a special fluid called cerebrospinal fluid. This fluid helps to protect the nerve tissue to keep it healthy, and remove waste products.
(c) Pituitary gland present in the brain is known as the master gland.

4. What is ‘hydrotropism’? Describe an experiment to demonstrate ‘hydrotropism’.
Answer. ‘Hydrotropism’ is the directional growth of a plant part in response to water. For example, roots show hydrotropism as they grow towards water in the soil and are positively hydrotropic.
An experiment to demonstrate hydrotropism is as follows:

1.  A porous pot filled with water is taken and inserted in a tub filled with dry sand.
2. A freshly germinated pea seedling is sowed in the sand.
3. As water is not available in sand, the root growing will bend towards the porous pot filled with water.
4. A hydrotropic curvature of the root is observed as it grows towards water.
5. This bending of root shows the movement in response towards water.

5. What are ‘hormones’? State one function of each of the following hormones:
(i) Thyroxine (ii) Insulin
Answer. Hormones are the chemical substances which coordinate and control the activities of living organisms and also their growth. The term hormone was introduced by Bayliss and Starling.
(i) Function of Thyroxine: This hormone regulates the metabolism of carbohydrates and fats.
(ii) Function of insulin: This hormone helps in regulating sugar level in the blood.

6. What is the function of receptors in our body? Think of situation where receptors do not work properly. What problems are likely to arise?
Answer. Receptors are present in our all parts of the body for example in skin, eye, nose tongue etc. They detect the signals and then send them to brain in the form of electrical signals. If these receptors are damaged then it they will not detect the input which leads to the harm for our body in dangerous situation.

7. Draw neat diagram of human brain and label on it the following parts :
(i) Midbrain (ii) Pituitary gland
Answer.

8.Write one example each of the following tropic movements :
(i) Positive phototropism (ii) Negative phototropism
(iii) Positive geotropism (iv) Negative geotropism
(v) Hydrotropism (vi) Chemotropism
Answer.
(i) Positive phototropism: shoots growing towards light.
(ii)Negative phototropism: roots growing away from light towards ground.
(iii) Positive geotropism: growth of roots towards earth due to the pull of the earth.
(iv)Negative geotropism: shoots growing away from the earth.
(v) Hydrotropism: roots growing towards the source of water.
(vi)Chemotropism: growth of pollen tubes towards the ovules.

9.(a) Name the hormone which is released into the blood when its sugar level rises. Explain the need of Chemical communication in multicellular organisms the organ which produces this hormone and its effect on blood sugar level. Also mention the digestive enzymes secreted by this organ with one function of each.
(b) Explain the need of Chemical communication in multicellular organisms.
Answer.
(a) Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the a-cells that regulates glucose levels in the blood.
In order for multicellular organisms to function properly, their cells must communicate. For instance, your muscles must contract when your brain sends a message to contract.
Pancreas produces insulin and p-cells which increase glucose in blood. It also – produces digestive enzyme (pancreatic amylase).
(b) Cell-to-cell signaling is a critical component of coordinating cellular activities. Through this communication, messages are carried from signaling cells to receiving cells, also known as target cells. This signaling occurs with proteins and other types of signaling molecules. Other things which happens in our body due to cell communication are – growth and development, cellular reproduction, tissue repair, sensing pain, etc.

10 (a) Explain how auxins help in bending of plant stem towards light.
(b) State the objective of the experiment for which experimental set-up is shown in the given diagram.
Answer.
(a) In plant shoots, the role of auxin is to cause a positive phototropism, i.e. to grow the plant towards the light. When light is incident on a plant from one direction, it causes the auxins to redistribute towards the shaded side of the plant. One function of auxin is to cause cell elongation. The redistribution causes the cells on the shaded side to elongate more than those on the side with the light shining on them. This causes the shoot to bend towards the light.
(b) The objective of the experiment is to show phototropic movement of plant.

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Question 1.
The muscular diaphragm that controls the size of the pupil is
(a) cornea
(b) ciliary muscles
(c) iris
(d) retina

Answer/Explanation
Answer: c
Explanation:
(c) Iris control the size of pupil.

2. Having two eyes facilitates in
   A : Increasing the field of view
   B : Bringing three-dimensional view
   C : Developing the concept of distance/ size
   Then the correct option is/are
   (a) A only
   (b) A and B only
   (c) B only
   (d) A, B and C

Answer: (d)

3. The black opening between the aqueous humour and the lens is called
   (a) retina
   (b) iris
   (c) cornea
   (d) pupil

Answer/Explanation
Answer: d
Explanation:
(d) The black opening between the aqueous humour and the eye lens is called pupil.

4. Near and far points of a young person normal eye respectively are
   (a) 0 and infinity
   (b) 0 and 25 cm
   (c) 25 cm and infinity
   (d) 25 cm and 150 cm.

Answer/Explanation
Answer: c
Explanation:
(c) Near point = 25 cm while far point = infinity.

5. The defect of vision in which the person is able to see distant object distinctly but cannot see nearby objects clearly is called
   (a) Long-sightedness
   (b) Far-sightedness
   (c) Hypermetropia
   (d) All above

Answer/Explanation
Answer: d
Explanation:
(d) Hypermetropia is also called long-sightedness or far-sightedness.

6. The ability of eye lens to adjust its focal length to form a sharp image of the object at varying distances on the retina is called
(a) Power of observation of the eye
(b) Power of adjustment of the eye
(c) Power of accommodation of the eye
(d) Power of enabling of the eye

Answer/Explanation
Answer: c
Explanation:
(c) It is called power of accommodation of the eye.

7. Myopia and hypermetropia can be corrected by
   (a) Concave and plano-convex lens
   (b) Concave and convex lens
   (c) Convex and concave lens
   (d) Plano-concave lens for both defects.

Answer/Explanation
Answer: b
Explanation:
(b) Myopia is corrected by using of suitable power of concave lens while hypermetropia is corrected by convex lens.

8. Bi-focal lens are required to correct
   (a) astigmatism
   (b) coma
   (c) myopia
   (d) presbyopia

Answer/Explanation
Answer: d
Explanation:
(d) Bifocal lens are required to correct the presbyopia. Upper point of bifocal lens consists of concave lens used for distant vision while lower point consists of convex lens facilitate near vision.

9. The defective eye of a person has near point 0.5 m and point 3 m. The power far corrective lens required for
(i) reading purpose and
(ii) seeing distant objects, respectively are:
(a) 0.5 D and +3D
(b) +2D and – (\frac{1}{3}) D
(c) – 2D and + (\frac{1}{3})D
(d) 0.5 D and-3.0 D

Answer/Explanation
Answer: b
Explanation:
(b) For reading purpose

10. The image formed on the retina of the human eye is
    (a) virtual and inverted
    (b) real and inverted
    (c) real and erect
    (d) virtual and erect

Answer/Explanation
Answer: b
Explanation:
(b) Eye lens is convex in nature. So, image formed by it on the retina is real and inverted.

11. When white light enters a prism, it gets split into its constituent colours. This is due to
    (a) different refractive index for different wavelength of each colour
    (b) each colours has same velocity in the prism.
    (c) prism material have high density.
    (d) Scattering of light

Answer/Explanation
Answer: a
Explanation:
(a) Dispersion takes place because refractive index of the material of prism is different for different wavelength.

12.
The air layer of atmosphere whose temperature is less then the hot layer behave as optically
(a) denser medium
(b) rarer medium
(c) inactive medium
(d) either denser or rarer medium

Answer/Explanation
Answer: a
Explanation:
(a) The cold air layer of the atmosphere acts as a optically denser medium than hot air because the molecules are closely packed together.

13. Refraction of light by the earth’s atmosphere due to variation in air density is called
    (a) atmospheric reflection
    (b) atmospheric dispersion
    (c) atmospheric scattering
    (d) atmospheric refraction

Answer/Explanation
Answer: d
Explanation:
(d) This phenomena is called atmospheric refraction.

14. The deflection of light by minute particles and molecules of the atmosphere in all direction is called __ of light.
    (a) dispersion
    (b) scattering
    (c) interference
    (d) tyndell effect

Answer/Explanation
Answer: b
Explanation:
(b) The said phenomenon is called scattering of light.

15. One cannot see through the fog, because
    (a) refractive index of the fog is very high
    (b) light suffers total reflection at droplets
    (c) fog absorbs light
    (d) light is scattered by the droplets

Answer/Explanation
Answer: d
Explanation:
(d) Objects are not visible through the fog because droplets scatter the light rays.

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Question 1. A wire of length /, made of material resistivity ρ is cut into two equal parts. The resistivity of the two parts are equal to,
(a) ρ
(b) (\frac{\rho}{2})
(c) 2 ρ
(d) 4 ρ

Answer/Explanation
Answer: a
Explanation:
(a) Resistivity of the material depends only on the nature of material not dimensions.

2. A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of
   (a) more length
   (b) less radius
   (c) less length
   (d) more radius

Answer/Explanation
Answer: d
Explanation:
(d) In order to get the working of heater properly, fused wire of higher rating must be used

3. A battery of 10 volt carries 20,000 C of charge through a resistance of 20 Ω. The work done in 10 seconds is
   (a) 2 × 103 joule
   (b) 2 × 105joule
   (c) 2 × 104 joule
   (d) 2 × 102 joule

Answer/Explanation
Answer: b
Explanation:
(b) W= qV= 20000 × 10 = 2,00, 000 = 2 × 105 J

4. A boy records that 4000 joule of work is required to transfer 10 coulomb of charge between two points of a resistor of 50 Ω. The current passing through it is
   (a) 2 A
   (b) 4 A
   (c) 8 A
   (d) 16 A

Answer/Explanation
Answer: c
Explanation:
(c) Work done in transferring the charge
W= qV = qlR …….. (V = IR)

5. A cooler of 1500 W, 200 volt and a fan of 500 W, 200 volt are to be used from a household supply. The rating of fuse to be used is
   (a) 2.5 A
   (b) 5.0 A
   (c) 7.5 A
   (d) 10 A

Answer/Explanation
Answer: d
Explanation:
(d) Total power used, P = P1 + P1 = 1500 + 500 = 2000 W.
Current drawn from the supply,.

6. To get 2 Ω resistance using only 6 Ω resistors, the number of them required is
   (a) 2
   (b) 3
   (c) 4
   (d) 6

Answer/Explanation
Answer: b
Explanation:
(b) Three resistors of 2 Ω is required to get 6 Ω because resultant is more than individual so they all must be connected in series.

7. The effective resistance between A and b
   (a) 4Ω
   (b) 6Ω
   (c) May be 10 Ω
   (d) Must be 10 Ω

Answer/Explanation
Answer: a
Explanation:
(a) 6 Ω is shorted so effective resistance is 4 Ω.

8. Two devices are connected between two points say A and B in parallel. The physical quantity that will remain the same between the two points is
   (a) current
   (b) voltage
   (c) resistance
   (d) None of these

Answer/Explanation
Answer: b
Explanation:
(b) In parallel combination, voltage remains same across two points.

9. The least resistance obtained by using 2 Ω, 4 Ω, 1 Ω and 100 Ω is
   a) < 100 Ω (b) < 4 Ω (c) < 1 Ω (d) > 2 Ω

Answer/Explanation

Answer: cExplanation:
(c) In parallel combination, the equivalent resistance is smaller than the least resistance used in the circuit.

10. Two wires of same length and area, made of two materials of resistivity ρ1 and ρ2 are connected in parallel V to a source of potential. The equivalent resistivity for the same length and area is

Answer/Explanation
Answer: b
Explanation:
(b) Equivalent resistance in parallel combination is (\frac{1}{R_{P}}=\frac{1}{R_{1}}+\frac{1}{R_{2}})
For the same length and area of cross-section, R ∝ p (resistivity)

11. Calculate the current flows through the 10 Ω resistor in the following circuit.

MCQ Questions for Class 10 Science Electricity with Answers 5
(a) 1.2 A
(b) 0.6 A
(c) 0.2 A
(d) 2.0 A

Answer/Explanation
Answer: b
Explanation:
(b) In parallel, potential difference across each resistor will remain same. So, current through 10 Ω resistor
I = (\frac{V}{R}=\frac{6}{10}) = 0.6 A

12. Two resistors are connected in series gives an equivalent resistance of 10 Ω. When connected in parallel, gives 2.4 Ω. Then the individual resistance are
    (a) each of 5 Ω
    (b) 6 Ω and 4 Ω
    (c) 7 Ω and 4 Ω
    (d) 8 Ω and 2 Ω

Answer/Explanation
Answer: b
Explanation:
(b) In series, Rs = R1 + R2 = 10 Ω

13. If R1 and R2 be the resistance of the filament of 40 W and 60 W respectively operating 220 V, then
    (a) R1 < R2
    (b) R2 < R1
    (c) R1 = R2
    (d) R1 ≥ R2

Answer/Explanation
Answer: b
Explanation:
(b) Using power, P = (\frac{V^{2}}{R}) or R = (\frac{V^{2}}{P})
For the same voltage, R ∝ (\frac{1}{P})
More the power, lesser the resistance.
Accordingly, R2 < R1

14. A wire of length /, made of material resistivity ρ is cut into two equal parts. The resistivity of the two parts are equal to,
(a) ρ
(b) (\frac{\rho}{2})
(c) 2 ρ
(d) 4 ρ

Answer/Explanation
Answer: a
Explanation:
(a) Resistivity of the material depends only on the nature of material not dimensions.

15.What is the maximum resistance which can be made using five resistors each of 1/5 W? [NCERT Exemplar Problems]
(a) 1/5 Ω
(b) 10 Ω
(c) 5 Ω
(d) 1 Ω

Answer/Explanation
Answer: d
Explanation:
(d) Series combination provide the maximum resistance

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1. Magnetic effect of current was discovered by
(a) Oersted
(b) Faraday
(c) Bohr
(d) Ampere

Answer/Explanation
Answer: a
Explanation:
(a) Oersted showed that electricity and magnetism were related phenomena.

2. Inside the magnet, the field lines moves
   (a) from north to south
   (b) from south the north
   (c) away from south pole
   (d) away from north pole

Answer/Explanation
Answer: a
Explanation:
(a) Magnetic field inside the magnet moves from south to north pole.

3. Relative strength of magnetic field at a point in the space surrounding the magnet is shown by the
   (a) length of magnet
   (b) thickness of magnet
   (c) degree of closeness of the field.
   (d) resistance offered by the surroundings

Answer/Explanation
Answer: a
Explanation:
(a) The force acting on the pole of another magnet by the crowded magnetic field lines is greater.

4. Which of the following statement is not correct about the magnetic field?
   (a) Magnetic field lines form a continuous closed curve.
   (b) Magnetic field line do not interest each other.
   (c) Direction of tangent at any point on the magnetic field line curve gives the direction of magnetic field at that point.
   (d) Outside the magnet, magnetic field lines go from South to North pole of the magnet.

Answer/Explanation
Answer:
Explanation:
(d) Outside the magnet, magnetic field line emerges from North-pole and moves towards south-pole.

5. By which instrument, the presence of magnetic field be determined?
   (a) Magnetic Needle
   (b) Ammeter
   (c) Galvanometer
   (d) Voltmeter

Answer/Explanation
Answer: d
Explanation:
(a) With the help of magnetic field, one can find the presence of magnetic field in a region by observing its deflection.

6. The pattern of the magnetic field produced by the straight current carrying conducting wire is
   (a) in the direction opposite to the current
   (b) in the direction parallel to the wire
   (c) circular around the wire
   (d) in the same direction of current

Answer/Explanation
Answer: a
Explanation:
(c) Magnetic field line around a current carrying straight conductor is represented by concentric circles.

7. The strength of magnetic field around a current carrying conductor is
   (a) inversely proportional to the current but directly proportional to the square of the distance from wire.
   (b) directly proportional to the current and inversely proportional to the distance from wire.
   (c) directly proportional to the distance and inversely proportional to the current
   (d) directly proportional to the current but inversely proportional the square of the distance from wire.

Answer/Explanation
Answer: b
Explanation:
• magnetic field strength increases on increasing the current through the wire.
• magnetic field strength decreases as the distance from the wire increases.

8. A current through a horizontal power line flows from south to North direction. The direction of magnetic field line 0.5m above it is
   (a) North
   (b) South
   (c) West
   (d) East

Answer/Explanation
Answer: a
Explanation:
(a) Apply right-hand thumb rule.

9. The nature of magnetic field line passing through the centre of current carrying circular loop is
   (a) circular
   (b) ellipse
   (c) parabolic
   (d) straight line

Answer/Explanation
Answer: d
Explanation:
(d) magnetic field line at the centre of current carrying loop appears as a straight line.

10. The strength of each of magnet reduces to half when it cut along its length into the equal parts magnetic field strength of a solenoid. Polarity of solenoid can be determined by
(a) use of compass needle
(b) Right hand thumb rule
(c) fleming left hand rule
(d) either (a) or (b)

Answer/Explanation
Answer: d
Explanation:
(d) both (a) and (b) can be use to determine the polarity of solenoid.

11. The factors on which one magnetic field strength produced by current carrying solenoids depends are
    (a) Magnitude of current
    (b) Number of turns
    (c) Nature of core material
    (d) All of the above

Answer/Explanation
Answer: d
Explanation:
(d) Factors shown in (a), (b) and (c).

12. A soft iron bar is introduced inside the current carrying solenoid. The magnetic field inside the solenoid
    (a) will decrease
    (b) will remains same
    (c) will increase
    (d) will become zero

Answer/Explanation
Answer: c
Explanation:
(c) Soft iron inside the current carrying solenoid act as an electromagnet.

13. When current is parallel to magnetic field, then force experience by the current carrying conductor placed in uniform magnetic field is
    (a) Twice to that when angle is 60°
    (b) Thrice to that when angle is 60°
    (c) zero
    (d) infinite

Answer/Explanation
Answer: a
Explanation:
(a) If the current direction is parallel to the magnetic field, then there will no force on the conductor exerted by the magnetic field.

14. A positive charge is moving upwards in a magnetic field directed towards north. The particle will be deflected towards
    (a) west
    (b) north
    (c) south
    (d) east

Answer: (a)
Explanation:
(a) Apply fleming’s left hand rule

15. Which of the following factors affect the strength of force experience by a current carrying conduct in a uniform magnetic field?
    (a) magnetic field strength
    (b) magnitude of current in a conductor
    (c) length of the conductor within magnetic field
    (d) All of above.

Answer/Explanation
Answer: d
Explanation:
(d) All the factors affect the strength of magnetic force.

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1. Energy can neither be created nor destroyed but still everybody discuss about the energy crisis because
   (a) Energy transform into different form continuously.
   (b) Usable form of energy is dissipated to the surroundings in less usable forms.
   (c) Energy is consumed and cannot be used again.
   (d) All of these

Answer/Explanation
Explanation:
(d) Energy can neither be created nor be destroyed but usable form is dissipated to surrounding in less usable farm which can’t be used again.

2. An ideal source of energy should have
   (a) higher calorific value
   (b) easy transportability
   (c) easy accessibility
   (d) All of these

Answer/Explanation
Answer: d
Explanation:
(d) These are the characterises of ideal source of energy.

3. Fossile fuels are
   (a) non-renewable source of energy
   (b) renewable source of energy
   (c) both (a) and (b)
   (d) Neither (a) nor (b)

Answer/Explanation
Answer: a
Explanation:
(a) Fossile fuels were formed over million of years ago and there are only limited reserve. So they are non-renewable source of energy.

4. Dead organisms are transformed into petroleum and natural gas in
   (a) presence of air
   (b) absence of air
   (c) presence of sunlight
   (d) none of the above

Answer/Explanation
Answer: b
Explanation:
(b) absence of air

5. Which of the following problem is associated with a burning of coal?
   (а) Carbon-dioxide emission
   (b) acid rain
   (c) ash with toxic metal supurity
   (d) all of these.

Answer/Explanation
Answer: d
Explanation:
(d) all of these.

6. Select the important factor for the site selection of a thermal power plant.
   (a) Distance from the populated area
   (b) Availability of fuel
   (c) Availability’ of water
   (d) Cost of plant

Answer/Explanation
Answer: c
Explanation:
(c) Water is required to produce steam. Thermal power plants are setup near the coal field and transmission of electricity is easy than transporting fuel.

7.The material used for interconnection the solar cells in the solar panel is
(a) silicon
(b) silver
(c) aluminium
(d) copper

Answer/Explanation
Answer: b
Explanation:
(b) Silver is the best conductor of electricity.

8. Hydropower plant are located in the
(a) desert area
(b) plane area
(c) hilly terrains
(d) none-of above

Answer/Explanation
Answer: c
Explanation:
(c) Hydroelectric power plant are generally located in high hilly areas where dam can easily be buit and large reservoir for storage of water can be obtained.

9. Biogas is a better fuel than animal dung cake because
   (a) biogas has lower calorific value.
   (b) animal dung cake has high calorific value
   (c) biogas bums smoke and leaves no residue
   (d) biogas is used as a fuel for cooking only wheareas dung cake can be used for cooking, illuminant the lanterns.

Answer/Explanation
Answer: c
Explanation:
(c) Biogas has high calorific value and leave no residue, no smoke after burning and can be used for domestic purpose, running engins and in gas lanterns for illumination.

10. Which of the following organism produces biogas from cow drug sherry in the biogas plant?
    (a) aerobic bectria
    (b) anaerobic bectria
    (c) prolozoa
    (d) fungi

Answer/Explanation
Answer: b
Explanation:
(b) In the absence of oxygen, anaerobic micro-organism decomposed the compound of cow- dung sturry to generate biogas.

11. Wind is caused due to
    (a) uneven heating of earth’s surface
    (b) rotation of earth
    (c) local conditions
    (d) All of these

Answer/Explanation
Answer: d
Explanation:
(d) All are the factors that responsible for the blowing of wind.

12. What are the disadvantage of solar energy
    (a) A large surface area is required collect the solar
    (b) Daily average of solar energy varies from 4 to 7 kwh/m2
    (c) Highly hazardous toxic material is used in the manufacturing of solar device.
    (d) All of the above are disadvantages.

Answer/Explanation
Answer: d
Explanation:
(d) All the points given are the disadvantage age of using solar energy.

13. The temperature inside the solar cooker ranges from
    (a) 500-100°C
    (b) 100-140°C
    (c) 150-200°C
    (d) 70-80°C

Answer/Explanation

Sources of Energy Questions and Answer: bExplanation:
(b) The box type solar cooker have a range 100-140°C.

14. The use of reflector in the solar cooker is to
    (a) Decrease efficiency
    (b) create green house effect
    (c) increase efficiency
    (d) none of these

Answer/Explanation
Answer: c
Explanation:
(c) Reflectors (mirror) are used to focus the sun rays along with heat radiation inside the box to achieve high temperature.

15. Solar cells are made of
    (a) germanium
    (b) silicon
    (c) silver
    (d) aluminium

Answer/Explanation
Answer: b
Explanation:
(b) special grade silicon is used for making solar cells.

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Quick Revision Notes : Sources of Energy

NCERT Solution :Sources of Energy

IMPORTANT QUESTION :Sources of Energy

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