Extra Questions of Class 10 Science Chapter 14 Sources of Energy PDF Download

We have provided you with Extra and Important Questions from Class 10 Science Chapter 14 Sources of Energy. This Extra and Important Questions will help you to score 100% in your Board Exams. These extra questions will be helpful to revise the important topics and concepts.

Sources of Energy Class 10 Important Questions with Answers Science Chapter 14

Extra Questions for Class 10 Science Chapter 14 Very Short Answer Type

Question: Mention the purpose of blackening the interior of a solar cooker.

Answer: The purpose of blackening the interior of a solar cooker is that the black surface absorbs more heat radiations of incident solar energy (about 98%) as compare to white or other light coloured surface.

Question: Name the part of a biogas plant where reactions take place in the absence of oxygen.

Answer: Digester chamber.

Question: Name the kind of energy possessed by wind and the device used to harness it.

Answer: Kinetic energy, wind mill.

Question: List two non-conventional sources of energy.

Answer: Geothermal, solar, biomass, water, wind are the non-conventional sources of energy, (any two)

Question: A black surface absorbs more heat radiations as compared to a white or a reflecting surface under identical conditions. List two solar devices which make use of this property in their design.

Answer: Solar cooker, solar water heater.

Question: Name any two elements that are used in fabricating solar cells.

Answer: Germanium, Silicon.

Question: Why a solar cooker painted black form outside?

Answer: Black surface absorbs more heat as compared to white or reflecting surface under identical conditions.

Question: What is acid rain?

Answer: Acid rain: The rain containing the acidic oxides such as oxides of carbon, nitrogen and sulphur.

Question: Write the name of the substance whose vapours are used to run the turbine of the generator of ocean thermal energy plant.

Answer: Ammonia.

Question: Mention the minimum temperature difference required between surface water and water at a depth of upto 2 km in an ocean thermal energy plant.

Answer: 20 °C or 293 K in trapping geothermal energy

Question: Name one fuel used in nuclear reactor.

Answer: Uranium-235.

Question: Name any two elements that are used in fabricating solar cells.

Answer: Germanium, Silicon.

Question: Name the reaction responsible for large energy production in the sun.

Answer: Nuclear fusion.

Question: List two nutrients that the slurry left behind in the biogas plant contain.

Answer: Nitrogen and phosphorous.

Question: List two nutrients that the slurry left behind in the biogas plant contain.

Answer: Nitrogen and phosphorous.

Question: Biogas is also known as gobar gas. Justify.

Answer: Starting material for biogas is mainly cow dung. So, it is also known as gobar gas.

Question: Define fuel.

Answer: A substance that produces useful energy when it burns or undergoes a chemical or nuclear reaction. The fuel such as coal, wood, oil, or gas provides energy when burned.

Extra Questions for Class 10 Science Chapter 14 Short Answer Type

Question: Bio gas is considered to be a boon to the farmers. Give reasons.


1. It is the source of excellent manure, rich in nitrogen and phosphorous which can be obtained from the biogas plant in addition to biogas.

2. It provides the safe, efficient and profitable disposal method for bio-waste and sewage material.

Question: What are the advantages of nuclear energy?

Answer: Advantages of nuclear energy are:

  • A small quantity of nuclear fuel is needed to produce a large amount of useful energy.
  • Nuclear power plant produces less atmospheric pollution than thermal power plants, if the nuclear fission reaction is performed properly.
  • Small amount of nuclear fuel can run a nuclear power plant over a long period of time. There is no need of inserting the nuclear fuel in the nuclear reactor again and again in a short period as in case of thermal power plant.

Question: What is a solar cell panel? Mention any three of its applications.

Answer: A large number of solar cells combined in an arrangement to obtain large electrical power is called solar cell panel.

Applications of solar cell panel are:It provides the electric power for the:

  • working of artificial satellites stationed in outer space,
  • running of irrigation water pumps by the farmers in rural areas,
  • street lighting in remote areas.

Question: Out of two solar cookers, one was covered with a plane glass slab and the other was left open. Which of the two solar cookers will be more efficient and why?

Answer: The solar cooker which was covered with a plane glass slab would be more efficient. The glass lid allows the heat radiation from sun to enter the solar cooker but does not allow the reflected heat radiation to escape or go outside the box. Thus, heat trapped inside the box increases the temperature. Glass lid also reduces heat loss due to reflection.

Question: Mention any four limitations in harnessing wind energy on a large scale.

Answer: Limitations in harnessing wind energy are:

  1. Speed of wind is not available at all time and at all places.
  2. To establish the wind energy farm, a large area of land is needed.
  3. Speed of wind should be higher than 15 km/h to harness the wind energy.
  4. Construction of windmill and its installation is very expensive.

Question: How are the wastes produced in nuclear power plants different from those produced in a thermal power plants? What happens to the waste of a nuclear power plant?

Answer: The waste obtained from nuclear power plants is highly radioactive in nature which emits harmful radiations, whereas waste produced in a thermal power plant is non-radioactive.

Management of nuclear waste is given as follows:

  • Some products of nuclear waste are buried in sealed steel/lead containers for a long term storage, buried under the ground or dumped in vacated coal mines.
  • Other waste products transforms into less harmful products or to products with a shorter half life.

Question: Describe how hydro energy can be converted into electrical energy. Write any two limitations of hydro energy.

Answer: Conversion of hydro energy into electrical energy

  • High rise dams are constructed on the river to obstruct the flow of water to collect it at a suitable height. The stored water has a lot of potential energy.
  • The water from a suitable height is allowed to fall on the blades of a turbine located at the bottom of a dam through a pipe.
  • Kinetic energy of flowing water rotates the turbine rapidly. Rotation of turbine helps the armature coil of generator to rotate rapidly in the magnetic field. Thus, hydroelectricity is generated.

Limitations of hydro energy:

  • All river-sites are not suitable for construction of dams.
  • Large ecosystems are destroyed when submerged under the water in dam.

Question: Define process of nuclear fission. Writ the steps involved in generating electricity in a nuclear reactor.

Answer: Nuclear Fission: The process in which a heavy nucleus (such as uranium, plutonium or thorium) is broken into two nearly equal fragments when bombarded with low-energy neutrons and a tremendous amount of energy is released. This process is called nuclear fission.

Steps involved in generating electricity:

  1. The fuel rods full of uranium pellets are placed in a nuclear reactor chamber.
  2. Low-energy neutrons are bombarded on uranium fuel rod.
  3. A self-sustaining fission chain reaction starts that releases energy at a controlled rate.
  4. With this heat the reactor converts water to steam at a high temperature and pressure.
  5. This high temperature and pressure steam spins generator turbines producing electricity.
  6. The steam cools back into water, which can then be used over again.

Question: State any three reasons to justify that LPG is considered as an ideal fuel.

Answer: LPG is considered as an ideal fuel because

  1. It is easy to store, handle and transport.
  2. It produces large amount of heat on burning.
  3. It does not leave any residue on burning.

Question: Distinguish between renewable and non-renewable sources of energy. Also give an example of each of these sources.


Extra Questions for Class 10 Science Chapter 14 Long Answer Type

Question: Write a short note on geothermal energy.


  • Energy harnessed from the heat of the Earth is called geothermal energy.
  • Magma is formed when this heat melts the rocks. The molten rocks and hot gases are called magma.
  • The magma gets collected at some depths below the earth’s surface. These places are called “hot spots’.
  • When underground water comes in contact with these hot spots, it changes into steam, which can be used to generate electricity.

Advantages of geothermal energy:

  • Renewable.
  • Cost of production is not much.

Disadvantages of geothermal energy:

  • Only few sites available for harnessing energy.
  • Expensive to set up.

Question: What is biomass? Explain the principle and working of a biogas plant . Write down its advantages.

Answer: Biomass is a source of conventionally used fuels that are used in our country, e.g., cow dung cakes, fire-wood, coal, charcoal.

Biogas: It is a mixture of gases produced during the decomposition of biomass in the absence of oxygen.Methane is the major component of biogas. (Biogas contains 75% methane, carbon dioxide, hydrogen and hydrogen sulfide).

Biogas plant: Animal dung, sewage, crop residues, vegetable wastes, poultry droppings, etc. are used to produce biogas in biogas plants

Construction and working:

The plant has a dome-like structure built with bricks. A slurry of cow dung and water is made in the mixing tank from where it is fed into the digester. The digester is a sealed chamber in which there is no oxygen. Anaerobic microorganisms, that do not require oxygen, decompose or breakdown complex compound of cow dung slurry and produce methane, carbon dioxide, hydrogen and hydrogen sulfide.

Advantages of biogas

  • It burns without smoke and leaves no residue.
  • Its heating capacity is high.
  • The slurry of biogas plant is used as an excellent manure, rich in nitrogen and phosphorus.

Question: Write down construction, advantages and limitations of a solar cooker.


Solar cooker: Construction:

Outer surface of the solar cooker is painted with black colour and a glass plate is used as cover.Black colour absorbs more heat and the glass plate traps solar radiation by greenhouse effect. Mirror reflects the light.

Advantages of solar cookers

  • Eco friendly
  • Renewable
  • Used in rural areas.
  • Retains all the nutrients in food due to slow cooking.

Disadvantages of solar cooker

  • Silicon cells are expensive.
  • Solar radiations are not uniform over the Earth’s surface.
  • Cannot be used at night or on cloudy days.
  • Cannot be used to make chapattis for frying as these require a temperature of 140°C or more. (Maximum temperature of 100°C only can be achieved in a solar cooker.)

Question: What is hydroelectric power plant? Write down its advantages and disadvantages.


Hydroelectric power plant: A conventional renewable source of energy is obtained from water falling from a great height. Dams are constructed to collect water flowing in high altitude rivers. The stored water has a lot of potential energy. When water is allowed to fall from a height, potential energy changes to kinetic energy, which rotates the turbines to produce electricity.


  • It is clean and non polluting source of energy.
  • Hydropower is renewable source of energy.


  • Highly expensive to construct.
  • Dams cannot be constructed on all river sites.
  • Large areas of human habitation and agricultural fields get submerged.
  • People face social and environmental problems.

Question: Which process is used to harness nuclear energy? Explain briefly.

Answer: Nuclear energy is produced by a process called nuclear fission. During this process, the nucleus of a heavy atom (such as uranium, plutonium or thorium) when bombarded with low-energy neutrons, can be split apart into lighter nuclei. The process releases a tremendous amount of heat energy. The released energy can be used to produce steam which is used to produce electricity.

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