Study MaterialsNCERT SolutionsNCERT Solutions for Class 10Ncert Solutions for Class 10 Science Chapter 14 Sources of energy

Ncert Solutions for Class 10 Science Chapter 14 Sources of energy

This chapter has been withdrawn from the CBSE Revised Term-wise Syllabus 2021-22.

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      Chapter 14 _SOURCES OF ENERGY


      1.What is a good source of energy?

      A. i) A good source of energy does a large amount of work per unit volume or mass

      ii) It is easily accessible

      iii) It is easy to store and transport

      iv) It is economical

      v) It produces less amount of smoke

      2. What is a good fuel?

      A.i) It has low cost and easily available

      ii) It has high calorific value, i.e, it produces large amount of heat on burning.

      iii) It has an ignition temperature that is well above the normal temperature

      iv) It produce less smoke on burning

      3.If you could use any source of energy for heating your food, which one would you use and


      A.We would use microwave oven for heating the food as it heats it uniformly and cleanly with out loss

      in its nutritional value.


      Natural gas can be used for heating and cooking food because it is a clean source of energy. It does

      not produce huge amount of smoke on burning. Although it is highly inflammable, it is easy to use,

      transport, and it produces a huge amount of heat on burning.

      4.What are the disadvantages of fossil fuels?

      A.The disadvantages of fossil fuels are as follows:

      i) Burning of coal and petroleum produces a lot of pollutants causing air pollution

      ii) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain, which affects

      the soil fertility and potable water.

      iii) Burning of fossil fuels produces gases such as carbon dioxide that causes green house effect

      and global warming.

      5.Why are we looking at alternate sources of energy?

      A.Fossil fuels, which have been traditionally used by human beings as an energy sources, are non

      renewable sources of energy. These sources of energy are limited and cannot replenish on their own.

      They are being consumed at a large rate. If this rate of consumption continues, then the fossil fuels

      would be exhausted from the earth. Therefore, we have to conserve the energy sources. Hences, we

      should look for alternate sources of energy.

      6.How has traditional use of wind and water energy been modified for our convenience?

      A.Traditionally, waterfalls were used as a source of potential energy which was converted to electricity

      with the help of turbines. Since waterfalls are few in number, water dams have been constructed in

      large number. Now a days, hydro – dams are used in order to harness potential energy of stored water.In water dams, water falls from a height on the turbine, which produces electricity.

      Earlier, the windmills were used to harness wind energy to do mechanical work such as lifting drawing water from a well. Today, wind mills are used to generate electricity. In windmills, the kinetic energy of wind is harnessed and converted into electricity. The rotatory motion of the

      blades turns the turbine of the electric generator to generate electricity

      7.What kind of mirror – concave, convex or plane mirror – would be best suited for use in a solar

      cooker ? why ?

      A.A solar cooker uses heat of the sunlight to cook and heat food. A mirror is used in order to reflect and focus sunlight at a point. A concave mirror is used in a solar cooker for this purpose. The mirror

      focuses all the incident sunlight at a point. The temperature at that point increases, thereby cooking

      and heating the food placed at that point.

      8.What are the limitations of the energy that can be obtained from the oceans?

      A.The forms of energy that can be obtained from the ocean are tidal energy, wave energy, and ocean

      thermal energy. There are several limitations in order to harness these energies.

      i) Tidal energy depends on the relative positioning of the earth, moon, and the sun.

      ii) High dams are required to be built to convert tidal energy into electricity

      iii) Very strong waves are required to obtain electricity from wave energy

      iv) To harness ocean thermal energy efficiently, the difference in the temperature of surface

      water (hot) and the water at depth (cold) must be 20ºC or more.

      9.What is geothermal energy?

      A.Geothermal power plants use heat of the earth to generate electricity. This heat energy of the earth is

      known as geothermal energy.

      When there are geological changes, the molten rocks present in the core of the earth are pushed to the earth’s crust. This forms regions of hot spot. Steam is generated when the underground water comes in contact with these hot spots forming hot springs. This trapped steam is used to generate

      electricity in the geothermal power plants.

      10.What are the advantages of nuclear energy? (Understanding)

      A.The advantages of nuclear energy are as follows:

      a) Large amount of energy is produced per unit mass

      b) It does not produce smoke. It is a clean energy

      c) Fission of one atom of uranium produces 10 million times the energy released by burning of

      one atom of carbon.

      d) Fusion of four hydrogen atoms produces huge amount of energy approximately equal to

      27 MeV.

      11.Can any source of energy be pollution – free ? Why or why not?

      A.No source of energy can be pollution – free. It is considered that solar cells are pollution – free.

      However, even their making causes environmental damage indirectly.

      Also, in the case of nuclear energy, there is no waste produced after the fusion reactions. However, it

      is not totally pollution – free. To start the fusion reaction, approximately 107 K temperature is required, which is provided by fission reactions. The wastes released from fission reactions are very hazardous.

      Hence, no source of energy is pollution free

      12.Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG?

      Why or why not?

      A.Hydrogen gas is cleaner than CNG. CNG contains hydrocarbons. Therefore, it has carbon contents.

      Carbon is a form of pollutant present in CNG. On the other hand, hydrogen is waste – free. The

      fusion of hydrogen does not produce any waste. Hence, hydrogen is cleaner than CNG.

      13.Name two energy sources that you would consider to be renewable. Give reasons for your


      A.Two renewable sources of energy are as follows:

      a) Sun : The energy produced from the sun is known as solar energy. Solar energy is prodced by

      the fusion of hydrogen into helium, fusion of helium into other heavy elements, and so on. A

      large amount of hydrogen and helium is present in the sun. Therefore, solar energy can replenish

      on its own. The sun had 5 billion years more to burn. Hence, solar energy is a renewable source

      of energy.

      b) Wind : Wind energy is derived from air blowing with high speed. Wind energy is harnessed

      by windmills in order to generate electricity. Air blows because of uneven heating of the earth.

      Since the heating of the earth will continue forever, wind energy will also be available forever.

      14.Give the names of two energy sources that you would consider to be exhaustible. Give reasons

      for your choices.

      A.Two exhaustible energy sources are as follows :

      a) Coal : It is produced from dead remains of plants and animals that remain buried under the

      earth’s crust for millions of years. It takes millions of years to produce coal. Industrialization

      has increased the demand of coal. However, coal cannot. replenish with in a short period of

      time. Hence, it is a non renewable or exhaustible source of energy.

      b) Wood : It is obtained from forests. Deforestation at a faster rate has caused a reduction in the

      number of forests on the earth. It takes hundreds of years to grow a forest. If deforestation is

      continued at this rate, then there would be no wood left on the earth Hence, wood is an exhaustible

      source of energy.


      1.A solar water heater cannot be used to get hot water on

      a) A sunny day b) a cloudy day c) a hot day d) a windy day

      A.(b) A solar water heater uses solar energy to heat water. It requires bright and intense sunlight to

      function properly. On a cloudy day, the sunlight reflects back in the sky from the clouds and is unable to reach the ground. Therefore, solar energy is not available for the solar heater to work properly.

      Hence, solar water heater does not function on a cloudy day

      2.Which of the following is not an example of a bio – mass energy source?

      a) Wood b) Gobar gas c) Nuclear energy d) Coal

      A.(c) Bio – mass is a source of energy that is obtained from plant materials and animal wastes. Nuclear

      energy is released during nuclear fission and fusion. In nuclear fission, uranium atom is bombarded

      with low – energy neutrons. Hence, uranium atom splits into two relatively lighter nuclei. This reaction produces huge amount of energy. In nuclear fusion reaction, lighter nuclei are fused together to form a relatively heavier nucleus. This reaction produces tremendous amount of energy. Hence,

      nuclear energy is not an example of bio – mass energy source.

      3.Most of the source of energy we use represent stored solar energy. Which of the following is

      not ultimately derived from the sun’s energy?

      a) Geothermal energy b) wind energy c) nuclear energy d) bio – mass

      A.(c) Nuclear energy is released during nuclear fission and fusion. In nuclear fission, uranium atom is

      bombarded with low – energy neutrons. Hence, uranium atom splits into two relatively lighter nuclei.

      This reaction produces huge amount of energy. In nuclear fusion reaction. lighter nuclei are fused

      together to form a relatively heavier nuclei. The energy required to fuse the lighter nuclei is provided

      by fission reactions. This reaction produces tremendous amount of energy. These reactions can be

      carried out in the absence or presence of sunlight. There is no effect of sunlight on these reactions.

      Hence, nuclear energy is not ultimately derived from sun’s energy.

      Geothermal energy, wind energy, and bio – mass are all ultimately derived from solar energy.

      4.Compare and contrast fossil fuels and the sun as direct sources of energy.

      A.Fossil fuels are energy sources such as coal and petroleum, obtained from underneath the earth’s

      crust. They are directly available to human beings for use. Hence, fossil fuels are the direct source of

      energy. These are non – renewable sources of energy because these cannot be replenished in nature.

      Fossil fuels take millions of years for their formation. If the present fossil fuel of the earth gets exhausted, its formation will take several years. Fossil fuels are also very costly.

      On the other hand, solar energy is a renewable and direct source of energy. The sun has been

      shining for several years and will do so for the next five billion years. Solar energy is available free

      of cost to all in unlimited amount.It replenishes in the sun itself.

      5.Compare and contrast bio mass and hydro electricity as source of energy.

      A.Bio – mass and hydro – electricity both are renewable sources of energy. Bio – mass is derived from

      dead plants and animal wastes. Hence, it is naturally replenished. It is the result of natural processes.

      Wood, gobar gas, etc. are some of the examples of bio – mass.

      Hydro – electricity, on the other hand, is obtained energy stored in water at a height. Energy

      from it can be produced again and again. It is harnessed from water and obtained from mechanical


      6.What are the limitations of extracting energy from

      a) the wind b) waves c) tides

      A.a) Wind energy is harnessed by windmills. One of the limitations of extracting energyfrom wind

      is that a windmill requires wind of speed more than 15 km/h to generate electricity. Also, a

      large number of windmills are requried, which covers a huge area.

      b) Very strong ocean waves are required in order to extract energy from waves.

      c) Very high tides are required in order to extract energy from tides. Also, occurence of tides

      depends on the relative positions of the sun, moon, and the earth.

      7.On what basis would you classifty energy sources as

      a) renewable and non – renewable?

      b) exhaustible and inexhaustible?

      Are the options given in (a) and (b) the same?

      A.a) The source of energy that replenishes in nature is known as renewable source of energy. Sun

      wind, bio- mass, etc. are some of the examples of renewable sources of energy.

      b) Exhaustible sources are those sources of energy. which will deplete and exhaust after a few

      hundred years. Coal, petroleum, etc. are the exhaustible sources of energy.

      Inexhaustible resources of energy are those sources, which will not exhaust in future. These

      are unlimited. bio – mass is one of the inexhaustible sources of energy.

      8.What are the qualities of an ideal source of energy?

      A.An ideal source of energy must be :

      i) Economical

      ii) Easily accessible

      iii) Smoke/pollution free

      iv) Easy to store and transport

      v) Able to produce huge amount of heat and energy on burning.

      9.What are the advantages and disadvantages of using a solar cooker? Are there places where

      solar cookers would have limited utility?

      A.i) Solar cooker uses sun’s energy to heat and cook food. It is inexhaustible and clean renewable

      source of energy.

      ii) It does not produces smoke or other residue due to which the environment does not get polluted.

      iii) When food is cooked in solar cooker, all the nutrients are retained and do not get destroyed as

      it cooks food at a very low temperature.

      Disadvatages :

      i) It does not work without sunlight. Hence, on cloudy day, it becomes useless

      ii) The places where the days are two short or places with cloud covers round the year, have

      limited utility for solar cooker.

      iii) As the direction of sun change with respect to the earth, the direction of reflection of solar

      cooker has to be changed continuously.

      10.What are the environmental consequences of the increasing demand for energy? What steps

      would you suggest to reduce energy consumption?

      A.Industrialization increases the demand for energy. Fossil fuels are easily accessible sources of energy that fulfill this demand. The increased use of fossil fuels has a harsh effect on the environment. Too much exploitation of fossil fuels increases the level of green house gas content in the atmosphere, resulting in global warming and a rise in the sea level.

      It is not possible to completely reduce the consumption of fossil fuels. However, some measures can

      be taken such as using electrical appliance wisely and not wasting electricity. Unnecessary usage of

      water should be avoided. Efficiency of energy sources should be maintained by getting them regularly serviced. These small steps may help in reducing the consumption of natural resources and conserving them.


      NCERT Exemplar Solutions for Science Chapter 14 in Class 10 also are provided.

      Class 10 Science Chapter 14 CBSE Notes

      Chapter 14- Energy Sources NCERT Answers for 10th class Science

      In the assessment, this chapter is awarded one mark. In the prior year’s examination, a solitary question has been asked from this chapter.

      The following topics are covered in this chapter:

      14.1 What Is a Good Energy Source?

      14.2 Traditional Energy Sources

      14.3. Non-conventional or alternative energy sources

      14.4 Consequences for the Environment 

      14.5 How Long Will a Source of Energy Last Us?

      Exercising Schedule

      10 Questions for Exercise Solutions (3 MCQs, 3 long, 4 short)

      What is a Good Energy Source? – 4 Questions

      3 Questions on Non-Conventional Energy Sources

      2 Questions on Traditional Energy Sources

      1 Question on Environmental Consequences

      Chapter 14- Energy Sources NCERT Solutions for Class 10 Science

      Energy comes from a variety of places. These resources are categorized as follows:

      Renewable Energy

      Sources that aren’t renewable

      Renewable energy is energy that can be recharged and is derived from natural sources such as the sun, wind, and water. The energy derived from these natural sources can be turned into a variety of types of energy, including solar energy, which is commonly utilized in solar cookers, solar panels for power generation, solar batteries, and so on, and wind energy, which is used in windmills.

      Non-renewable energy is derived from natural resources that cannot be replaced once depleted. Non-renewable energy sources include coal, oil, and natural gas. The creation of these resources takes several years. In today’s world, these are frequently used. When compared to renewable resources, they are less eco-friendly because they emit a lot of pollution when burned.

      These energy sources have a number of benefits and drawbacks. As a result, they should be taken with caution. Non-renewable resources are rapidly depleting. Alternative energy sources are being sought that can be used in an environmentally responsible manner without depleting the environment.

      NCERT Solutions for Class 10 Science Chapter 14- Energy Sources: Key Aspects

      The greatest technique to assess oneself is to use NCERT Solutions.

      It aids in the comprehension of the principles.

      NCERT Solutions, developed by specialists after extensive research, present correct information.

      For better practice with questions from past year’s question papers, sample papers and MCQs are supplied.

      The questions and answers are useful in resolving any issues.

      NCERT Solutions for Class 10 Science Chapter 14 Frequently Asked Questions

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      The answers to the problems in the required textbook are found in the NCERT Solutions for Class 10 Science Chapter 14. The solutions are developed by INFINITY LEARN’S subject experts based on the students’ comprehension ability. Based on the CBSE norms and exam pattern, the faculty provides 100 percent correct and quality solutions. Every solution is given in simple language to help students gain confidence in their ability to perform well on-board exams.

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      Explain the drawbacks of fossil fuels, as discussed in NCERT Solutions for Class 10 Science Chapter 14.

      The following are some of the drawbacks of fossil fuels:

      The use of fossil fuels can pollute the environment.

      Acid rain is also caused by fossil fuels.

      Soil fertility declines, and the quality of portable water deteriorates.

      The combustion of fossil fuels releases harmful gases into the atmosphere, which is the primary cause of global warming.

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