NCERT Exemplar for Class 10 Science Chapter 14 - Sources of Energy (Book Solutions)

Multiple Choice Questions (MCQs)

1. Which of the following is a nonrenewable source of energy?

(a) Wood

(b) Sun

(c) Fossil fuels

(d) Wind

Ans: (c) Fossil fuels

Explanation: It takes millions of Years of the formation of fossil fuels. So, they cannot be renewed in the near future.

2. Acid rain happens because

(a) Sun leads to heating of the upper layer of the atmosphere

(b) burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere

(c) electrical charges are produced due to friction amongst clouds

(d) earth's atmosphere contains acids

Ans: (b) burning of fossil fuels release oxides of carbon, nitrogen and Sulphur in the atmosphere

Explanation: Acids are formed when carbon, nitrogen, and sulphur oxides react with rainwater. This causes acid rain.

3. Fuel used in thermal power plants is

(a) water

(b) uranium

(c) biomass

(d) fossil fuels

Ans: (d) fossil fuels

Explanation: Thermal power stations mostly use coal as a fuel. There is also the use of natural gas and petroleum gas.

4. In a hydropower plant

(a) Potential energy possessed by stored water is converted into electricity

(b) Kinetic energy possessed by stored water is converted into potential energy

(c) Electricity is extracted from water

(d) Water is converted into steam to produce electricity

Ans: (a) Potential energy possessed by stored water is converted into electricity

Explanation: Dams are used to hold water. The water that has been stored has potential energy. Potential energy is converted to kinetic energy when water is released from the dam. This kinetic energy is used to generate electricity by turning the turbine.

5. Which is the ultimate source of energy?

(a) Water

(b) Sun

(c) Uranium

(d) Fossil fuels

Ans: (b) Sun

Explanation: Fossil fuels are derived from biomass, which is produced through photosynthesis. We already know that photosynthesis converts solar energy into biomass. The sun drives the water cycle, and hence the kinetic energy in water is due to the sun. As a result, the sun is regarded as the ultimate source of energy.

6. Which one of the following forms of energy leads to the least environmental pollution in the process of its harnessing and utilisation?

(a) Nuclear energy

(b) Thermal energy

(c) Solar energy

(d) Geothermal energy

Ans: (c) Solar energy

7. Ocean thermal energy is due to

(a) energy stored by waves in the ocean

(b) temperature difference at different levels in the ocean

(c) pressure difference at different levels in the ocean

(d) tides arising out in the ocean

Ans: (b) temperature difference at different levels in the ocean

Explanation: A volatile liquid is boiled using energy from a heating surface. The turbine is turned by the vapours of this liquid. The vapours are then channelled into deeper waters to cool down.

8. The major problem in harnessing nuclear energy is how to 

(a) split nuclei?

(b) sustain the reaction?

(c) dispose of spent fuel safely?

(d) convert nuclear energy into electrical energy?

Ans: (c) dispose of spent fuel safely?

Explanation: A nuclear power plant's spent fuel includes highly radioactive material. This has the potential to be extremely destructive to both living things and the environment.

9. Which part of the solar cooker is responsible for the greenhouse effect?

(a) Coating with black colour inside the box

(b) Mirror

(c) Glass sheet

(d) Outer cover of the solar cooker

Ans: (c) Glass sheet

10. The main constituent of biogas is

(a) methane

(b) carbon dioxide

(c) hydrogen

(d) hydrogen sulphide

Ans: (a) Methane

11. The power generated in a windmill

(a) is more in the rainy season since damp air would mean more air mass hitting the blades

(b) depends on the height of the tower

(c) depends on wind velocity

(d) can be increased by planting tall trees close to the tower

Ans: (c) depends on wind velocity

Explanation: The turbine will spin faster if the wind velocity is higher. This will aid in the generating of additional electricity.

12. Choose the correct statement

(a) Sun can be taken as an inexhaustible source of energy

(b) There is infinite storage of fossil fuel inside the earth

(c) Hydro and wind energy plants are non-polluting sources of energy

(d) Waste from a nuclear power plant can be easily disposed off

Ans: (a) Sun can be taken as an inexhaustible source of energy

13. In a hydroelectric power plant more electrical power can be generated if waterfalls from a greater height because

(a) its temperature increases

(b) larger amounts of potential energy is converted into kinetic energy

(c) the electricity content of water increases with height

(d) more water molecules dissociate into ions

Ans: (b) larger amounts of potential energy is converted into kinetic energy

Explanation: As one grows taller, their potential energy increases.

14. Choose the incorrect statement regarding wind power

(a) It is expected to harness wind power to a minimum in open space

(b) The potential energy content of wind blowing at high altitudes is the source of wind power

(c) Wind hitting at the blades of a windmill causes them to rotate the rotation thus achieved can be utilized further

(d) One possible method of utilizing the energy of rotational motion of the blades of a windmill is to run the turbine of an electric generator

Ans: (b) The potential energy content of wind blowing at high altitudes is the source of wind power

Explanation: A windmill is powered by the kinetic energy of the wind.

15. Choose the incorrect statement

(a) We are encouraged to plant more trees so as to ensure a clean environment and also

provide biomass fuel

(b) Gobar-gas is produced when crops, vegetable wastes, etc., decompose in the

absence of oxygen

(c) The main ingredient of bio-gas is ethane and it gives a lot of smoke and also

produces a lot of residual ash

(d) Biomass is a renewable source of energy

Ans: (c) The main ingredient of bio-gas is ethane and it gives a lot of smoke and also produces a lot of residual ash

Explanation: Methane is the primary component of biogas. It burns cleanly and leaves no trace.

Short Answer Questions

16. Why is there a need to harness non-conventional sources of energy? Give two main reasons.

Ans: Two reasons for the need to harness non-conventional sources of energy are as follows:

(a) In the not-too-distant future, conventional sources will be depleted.

(b) Fossil fuel combustion pollutes the environment.

17. Write two different ways of harnessing energy from the ocean.

Ans: The following are two methods for obtaining energy from the ocean:

(a) Tidal energy and (b) ocean thermal energy are two types of energy.

18. What steps would you suggest to minimize environmental pollution caused by the burning of fossil fuels?

Ans: (i) Use of smokeless appliances.

(ii) Afforestation

19. What is the role of a plane mirror and a glass sheet in a solar cooker?

Ans: The sun is reflected by the plane mirror in the solar cooker, increasing the intensity of solar radiation. The solar cooker's heat is kept in by a glass sheet. To put it another way, the glass sheet creates a greenhouse effect.

20. Mention three advantages of a solar cell?

Ans: Solar cells contain no moving components, need no maintenance, and can be installed in remote locations.

21. What is biomass? What can be done to obtain bio-energy using biomass?

Ans: Biomass is a type of fuel made from organic matter. The following are some biomass-harvesting techniques: 

(a) Using firewood as fuel

(b) Using cow dung cakes as fuel

(c) Production of gobar gas

22. What are the limitations in obtaining energy from wind?

Ans: a. Energy cannot be harnessed continuously.

b. Wind farms require large areas.

c. minimum wind speed should be 15km/h.

Long Answer Questions

23. Which is the process used to harness nuclear energy these days? Explain it briefly.

Ans: Nuclear power stations use nuclear energy to generate electricity. A nuclear reactor, a boiler, and a turbine are all included.

(a) A nuclear reactor is a facility that performs nuclear fission. Nuclear fission produces a huge amount of energy.

(b) The heat generated by nuclear fission is used to boil water in order to generate steam.

(c) To generate power, steam is used to turn turbines.

24. How can solar energy be harnessed? Mention any two limitations in using solar energy. How are these limitations overcome?

Ans. Solar energy harvesting techniques include

Solar Cookers: A solar cooker is a very straightforward appliance. It's made out of a rectangular box with a mirror on top of it. The lid of the box is made of glass. The mirror is kept upright so that reflected sunlight can enter the enclosure. The box is where the utensils are kept. The box's heat is kept in by a glass lid on top.

Photovoltaic Cell: A photovoltaic cell is a type of solar cell. It transforms solar energy into electricity. The electrical energy generated must be stored in inverters so that it can be utilized at all times of the day and night.

Solar Furnace: A concave mirror is used to create a solar furnace. This furnace's heating device is kept in the center. The sun's heat is focused at the focus, which aids in the generation of a large amount of heat. The solar furnace can be used to heat water, and the steam produced can be used to generate power.

Solar Energy's Limitations:

(a) It can only be used in regions where there is lots of sunlight.

(b) Cannot be harnessed beyond a given range of possibilities.

(c) It is not possible to harness at night.

(d) Current technologies are prohibitively expensive.

Limitations can be avoided by using batteries to store electrical energy generated by solar cells.

25. Make a list of conventional and non-conventional sources of energy. Give a brief description of harnessing one non-conventional source of energy.

Ans:

Tidal Energy Harvesting Methods: A cylindrical structure is vertically put in coastal locations where tides come to harvest tide energy.

At the top of this cylinder is a turbine.

When the tide comes in, the cylinder fills with air. This spins the turbine, which generates power.

Air moves in the opposite direction when the tide goes out. This also rotates the turbine, resulting in the generation of energy.

26. Why is there a need for harnessing non-conventional sources of energy? How can energy be harnessed from the sea in different ways?

Ans: The following are the primary reasons for the necessity to harness non-conventional energy sources:

(a) Nonrenewable Fuels: We rely on fossil fuels as our primary source of energy. However, the production of fossil fuels takes millions of years. We are using them at such a rapid rate that they will not last for many years. They'd be completely spent sooner rather than later.

(a) Polluting fuels: The combustion of fossil fuels releases carbon, nitrogen, and sulphur oxides. These are noxious gases. A greenhouse gas is carbon dioxide. Even at low concentrations, carbon monoxide can be dangerous. Acid rain is caused by sulphur and nitrogen oxides. Increased occurrences of respiratory ailments are also a result of air pollution.

Various methods of extracting energy from the sea are as follows

(i) Wave energy

(ii) Tidal energy

(iii) Ocean thermal energy

27. What are the environmental consequences of using fossil fuels? Suggest the steps to minimize the pollution caused by various sources of energy including non-conventional sources of energy.

Ans: The following are the environmental effects of burning fossil fuels:

(a) Global warming is caused by increased carbon dioxide levels. Weather patterns are changing dramatically as a result of global warming.

(b) Acid rain is caused by sulphur and nitrogen oxides. Acid rain is hazardous to structures and monuments, as well as to living things.

(c) As air pollution levels rise, more people are developing respiratory illnesses.

(d) Smog is a significant issue in cities because it impairs visibility. It is inconvenient for pilots and drivers.

Steps to reduce pollution generated by various energy sources include:

The utilization of public transportation has increased.

Bicycle usage has increased.

Reduce, reuse, and recycle, as outlined in the three Rs of conservation. We can reduce the demand for energy by doing so. This will assist in the reduction of pollutants.

28. Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answer.

Ans: The sun is the most powerful generator of energy. It is true that the sun has provided energy to a variety of sources. The reasons behind this are as follows:

Plants use sun energy to produce biomass. This biomass was used to produce fossil fuels. As a result, the energy in fossil fuels came from the sun.

(a) As previously stated, the sun provides energy to firewood and gobar gas.

(b) The water cycle on Earth occurs as a result of the sun's heat. As a result, the sun is the source of kinetic energy in water.

(c) The sun heats the ocean, causing waves and ocean currents. As a result, the sun is at the root of various types of ocean energy.

(d) The earth was created after a component of the sun was used to form this planet. As a result, geothermal energy and nuclear power plant energy are both derived from the sun.

29. What is biomass? Explain the principle and working of a biogas plant using a labelled schematic diagram.

Ans: Biomass is a fuel that is obtained from organic materials.

Biogas production is based on the decomposition of organic waste. Methane makes up the majority of biogas. It produces very little smoke and leaves no trace when burned. It can be used as a source of cooking fuel. It can be used to generate electricity as well.

Biogas Plant Operation: 

(a) The biogas plant is fed a variety of farm waste. To form a slurry, this trash is combined together.

(b) The digester then receives the slurry. The digester is an airtight chamber that is devoid of oxygen.

(c) Slurry breakdown is carried out by anaerobic microorganisms in the digester. As a result, biogas is produced.

(d) Biogas is discharged through an outlet so that it can be used properly.

(e) The decomposed stuff is removed and utilized as manure.

An overview of NCERT Exemplar for Class 10 Science - Sources of Energy

This component gives required insights into the topic of Sources of energy from the Class 10 NCERT textbook. Having extra knowledge than that is given in the textbook will improve conceptual clarity and also help you gain maximum marks. This exemplar component of NCERT is carefully designed by the experts after a proper survey into the required concepts, previous year questions, and exam pattern. This Chapter helps the student to understand=d what are renewable and non-renewable sources of energy and how are they different, what are different sources of energy, advantages, and disadvantages of different energy resources.

Conservation of energy is a trending topic. So studying this Chapter will help students understand the best practices for sustainable use of energy resources. Students will also get to know about hydroelectric power plants, biogas power plants, thermal power plants. Have a look at the PDF of the exemplar material of this Chapter below for a better understanding. Students are recommended not to skip any concepts and have a comprehensive understanding of the Chapter for better scores. They are recommended to refer to previous year's questions and practice them thoroughly to improve scores in board exams.