NCERT Solutions For Class 10 Science Chapter 14 Sources of Energy

Sources of Energy Class 10 NCERT Solutions

NCERT Books Solutions For Class 10 Science Chapter 14 Sources of Energy

NCERT Solutions For Class 10 Science Chapter 14 Sources of Energy is the first stepping stone for a student in the competitive world. With the introduction of the CBSE Board Exam for class 10 a few years back, this has become an important gateway for a student as based on the results of class 10th a student selects his future stream of Science, Commerce, or Arts.

NCERT Solutions For Class 10 Science Chapter 14 Sources of Energy

Takshila Learning provides you with detailed and well explained NCERT Solutions for Class 10 of each chapter of each subject for NCERT Class 10. These NCERT Solutions help you to easily understand every concept so that you can score high in your CBSE Class 10 Board Exams.

Below you can find the NCERT solution for Class 10th Science. You can get a Solution for the all-important question of Class 10 Science Chapter 14 Sources of Energy”

Q1. What is a good source of energy?

Ans: A good source of energy fulfils the following criteria:

  • It produces a lot of heat in per unit mass.
  • It does a massive amount of work in per unit mass.
  • It is accessible easily.
  • It is easy to save and transport.
  • It is cost-effective.
  • It produces much less amount of smoke.



Q2. What is a good fuel?

Ans: A good fuel produces a large amount of heat on burning, does not produce a variety of smoke, and is effortlessly available.



Q3. If you could use any source of energy for heating your food, Which one would you use and why?

Ans: Natural gas is used for heating and cooking food because it’s a clean source of energy. It doesn’t produce huge amount of smoke on burning. Although it’s highly inflammable, it’s easy to use, transport, and it produces a large amount of warmth on burning.





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Q1. What are the disadvantages of fossil fuels?

Ans: The disadvantages of fossil fuels are as follows:

  • Burning of coal and petroleum produces plenty of pollutants causing pollution.
  • Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause air pollution, which affects the soil fertility and potable water.
  • Burning of fossil fuels produce gases like greenhouse emission that causes warming.



Q2. Why are we looking at alternate sources of energy?

Ans: Fossil fuels, which are traditionally utilised by individuals as an energy sources, are non-renewable sources of energy. These sources of energy are limited and can’t replenish on their own. They’re being consumed at an outsized rate. If this rate of consumption continues, then the fossil fuels would be exhausted from the world. Therefore, we’ve to conserve the energy sources. Hence, we should always search for alternate sources of energy.



Q3. How has the traditional use of wind and water energy been modified for our convenience?

Ans: Traditionally, waterfalls were used as a source of P.E. which was converted to electricity with the assistance of turbines. Since waterfalls are few in number, water dams are constructed in large numbers. Nowadays, hydro-dams are utilized in order to harness P.E. of stored water. In water dams, water falls from a height on the turbine, which produces electricity.

Earlier, the windmills were accustomed harness wind energy to try and do mechanical work like lifting/drawing water from a well. Today, windmills are accustomed generate electricity. In windmills, the mechanical energy of wind is harnessed and converted into electricity. The rotatory motion of the blades turns the turbine of the electrical generator to get electricity.





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Q1. What kind of mirror − concave, convex or plain − would be best suited for use in a solar cooker? Why?

Ans: A solar cooker uses heat of the sun to cook and heat food. A mirror is used in order to reflect and focus sunlight at a point. A concave mirror focuses all the incident sunlight at a point. This raises the temperature at that point, thereby cooking and heating the food placed at that point.



Q2. Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?

Ans: Hydrogen gas is cleaner than CNG as CNG contains hydrocarbons and so it has carbon contents. Carbon is a form of pollutant present in CNG and hydrogen is waste-free. The fusion of hydrogen does not produce any waste. Hence, hydrogen is cleaner than CNG.





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Q1. Can any source of energy be pollution-free? Why or why not?

Ans: No source of energy may be pollution-free. it’s considered that solar cells are pollution-free. However, even their making causes environmental damage indirectly.

Also, within the case of atomic energy, there’s no waste produced after the fusion reactions. However, it’s not totally pollution-free. to begin the fusion reactions, 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.



Q2. What are the limitations of the energy that can be obtained from the oceans?

Ans: The kinds of energy which will be obtained from the ocean are tidal energy, wave energy, and ocean thermal energy. There are several limitations so as to harness these energies.

  • Tidal energy depends on the relative positioning of the world, moon, and also the Sun.
  • High dams are required to be built to convert tidal energy into electricity.
  • Very strong waves are required to get electricity from wave energy.
  • To harness ocean thermal energy efficiently, the difference within the temperature of surface water (hot) and also the water at depth (cold) must be 20ºC or more.



Q3. What is geothermal energy?

Ans: The heat energy of the Earth is known as geothermal energy. Geothermal power plants use heat of the Earth to generate electricity.

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.



Q4. What are the advantages of nuclear energy?

Ans: The advantages of atomic energy are as follows:

  • great amount of energy is produced per unit mass.
  • It doesn’t produce smoke. it’s a clean energy.
  • Fission of 1 atom of uranium produces 10 million times the energy released by burning of 1 atom of carbon.
  • Fusion of 4 hydrogen atoms produces huge amount of energy approximately adequate to 27 MeV.





Page No. –  254


Q1. Name two energy sources that you would consider to be renewable. Give reasons for your choices.

Ans: Two renewable sources of energy are as follows:


  • Sun: The energy derived from the Sun is understood as alternative energy. Alternative energy is produced due to the fusion of hydrogen into helium, fusion of helium into other heavy elements, and so on. an Excessive amount of hydrogen and helium is present within the Sun. Therefore, alternative energy can replenish on its own. The Sun has 5 billion years more to burn. Hence, alternative energy may be a renewable source of energy.
  • 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.




Q2. Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.

Ans: Two exhaustible energy sources are as follows:

  • Coal: it’s produced from dead remains of plants and animals that remain buried under the earth’s crust for scores of years. It takes scores of years to supply coal. Industrialisation has increased the demand of coal. However, coal cannot replenish within a brief period of your time. Hence, it’s a non-renewable or exhaustible source of energy.
  • 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.





Page No. – 254


Q1. A solar water heater cannot be used to get hot water on

  • a sunny day
  • a cloudy day
  • a hot day
  • a windy day

Ans: (b) A solar heater uses alternative energy to heat water. It requires bright and intense sunlight to function properly. On a cloudy day, the daylight reflects back within the sky from the clouds and is unable to achieve the bottom. Therefore, alternative energy isn’t available for the heater to figure properly. Hence, solar heater doesn’t function on a cloudy day.



Q2. Which of the following is not an example of a bio-mass energy source?

  • wood
  • gobar gas
  • nuclear energy
  • coal

Ans: (c) Bio-mass is a source of energy that’s obtained from plant materials and animal wastes. Energy is released during fission and fusion. In 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 reaction reaction, lighter nuclei are fused together to create a comparatively heavier nuclei. This reaction produces tremendous amount of energy. Hence, energy isn’t an example of bio-mass energy source.

Wood may be a stuff, gobar gas is created from animal dung, and coal may be a fuel obtained from the buried remains of plants and animals. Hence, these are bio-mass products.



Q4. Compare and contrast fossil fuels and the Sun as direct sources of energy.

Ans: Fossil fuels are energy sources like coal and petroleum, which are obtained from underneath the Earth’s crust. They are directly available to human beings for use. So, fossil fuels are the direct source of energy. These are limited in amount. 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. The disadvantage is fossil fuels are 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.




Q5. Compare and contrast bio-mass and hydro electricity as sources of energy.

Ans: Bio-mass and hydro-electricity both are renewable sources of energy. Bio-mass springs from dead plants and animal wastes. Hence, it’s naturally replenished. It’s the results of natural processes. Wood, Gobar gas, etc. are a number of the samples of bio-mass.

Hydro-electricity, on the opposite hand, is obtained from the P.E. stored in water at a height. Energy from it will be produced again and again. it’s harnessed from water and obtained from mechanical processes.



Q6. What are the limitations of extracting energy from −

  • the wind?
  • waves?
  • tides?

Ans: (a) Wind energy is harnessed by windmills. one in all the constraints of extracting energy from wind is that a windmill requires wind of speed over 15 km/h to come up with electricity. Also, an outsized number of windmills are required, which covers an enormous area.


(b) Very strong ocean waves are required so as to extract energy from waves.


(c)Very high tides are required so as to extract energy from tides. Also, occurrence of tides depends on the relative positions of the Sun, moon, and also the Earth.




Q7. On what basis would you classify energy sources as

(a) renewable and non-renewable?

(b) exhaustible and inexhaustible?

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

Ans: (a) The source of energy that replenishes in nature is understood as renewable source of energy. Sun, wind, moving water, bio-mass, etc. are a number of the samples of renewable sources of energy. The source of energy that doesn’t replenish in nature is understood as non-renewable source of energy. Coal, petroleum, fossil fuel, etc. are a number of the samples of non-renewable sources of energy.


(b) Exhaustible sources are those sources of energy, which is able to deplete and exhaust after some hundred years. Coal, petroleum, etc. are the exhaustible sources of energy.

Inexhaustible resources of energy are those sources, which is able to not exhaust in future. These are unlimited. Bio-mass is one in all the inexhaustible sources of energy.

Yes. the choices given in (a) and (b) are a similar.




Q8. What are the qualities of an ideal source of energy?

Ans: An ideal source of energy must be:

  • Easily accessible.
  • Smoke/pollution free.
  • Easy to store and transport.
  • able to produce huge amount of warmth and energy on burning.




Q9. What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?

Ans: Solar cooker uses Sun’s energy to heat and cook food. it’s inexhaustible and clean renewable source of energy. it’s free for all and available in unlimited amount. Hence, operating a solar cooker isn’t expensive.

Disadvantage of a solar cooker is that it’s very expensive. It doesn’t work without sunlight. Hence, on cloudy day, it becomes useless.

The places where the times are too short or places with cloud covers around the year, have limited utility for solar cooker.



Q10. What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?

Ans: Industrialisation increases the demand for energy. Fossil fuels are easily accessible sources of energy that fulfil this demand. The increased use of fossil fuels incorporates a harsh effect on the environment. An excessive amount of exploitation of fossil fuels increases the extent of green house gas content within the atmosphere, leading to warming and an increase within the water level.

It is out of the question to completely reduce the consumption of fossil fuels. However, some measures is taken like using electrical appliances wisely and not wasting electricity. Unnecessary usage of water should be avoided. Conveyance system with mass transit must be adopted on an outsized scale. These small steps may help in reducing the consumption of natural resources and conserving them.

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