Sources of Energy: Science Class 10 Chapter 14 answers, notes

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The topic of Class 10 Science Chapter 14: Sources of Energy (NCERT, NBSE, SEBA, TBSE etc.), is the different types of energy that we use on a daily basis. The world depends on energy to function, and we use a variety of sources to power our daily activities. The two main types of these sources are exhaustible and inexhaustible. In contrast to finite resources like fossil fuels, which eventually run out, renewable resources like sunlight and wind do not deplete. It is, therefore, crucial to think about switching to more sustainable, green energy sources due to growing worries about pollution and climate change. Get here the questions, answers, textbook solutions, PDF, MCQs of this chapter.

a windmill, illustrating the chapter of class 10 science "sources of energy"

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1. What is a good source of energy?

Answer: A good energy source is one that can produce a lot of usable energy per unit of mass or volume. It should be affordable, readily available, and simple to store and transport.

2. What is a good fuel?

Answer: A fuel is considered to be a good fuel if it burns with little smoke while producing a lot of heat per unit volume or mass. It ought to have a lot of calories. Additionally, it should be simple to access, store, and transport.

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

Answer: Since LPG (liquid petroleum gas) is a clean energy source and doesn’t emit smoke when burned, it can be used to heat food. Additionally, it is simple to store and transport.

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1. What are the disadvantages of fossil fuels?

Answer: Following are a few drawbacks of using fossil fuels:

i. They are a non-renewable resource, so they could run out soon.
ii. They release dangerous chemicals like carbon dioxide,

Burning fossil fuels releases nitrogen and sulphur, which 

ii. contribute to air pollution and acid rain, and
iv. have a greenhouse effect.

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

Answer: As long as we continue using non-renewable energy sources at our current rate, we will eventually run out of them because it takes millions of years for coal and petroleum to form. We must therefore search for alternative sources of energy going forward in order to avoid such a situation.

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

Answer: In the past, windmills were employed to collect wind energy and use it to power mechanical tasks like lifting/drawing water from wells. The kinetic energy of the wind is now captured and transformed into electricity in windmills.

Previously used for transportation, water energy is now a good source for producing electricity. On the river, dams have been built to produce electricity. Utilizing waterfalls as a source of potential energy that was then transformed into electricity by turbines

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

Answer: The best mirror to use in a solar cooker is a concave one because it can focus the sun’s light rays on a point that will generate a lot of heat. which is necessary for the food to be cooked in the solar cooker.

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

Answer: Tidal energy, wave energy, and ocean thermal energy are various forms of energy that can be obtained from the sun. But there are several limitations to harness these energies. Those limitations are

(i) Tidal energy depends on the relative positioning of sun, moon and the earth
(ii) To harness the tidal energy large dams are needed to be built. The locations where such dams can be built are limited.
(iii) The cost of building such dams and maintaining them is also expensive.
(iv) For wave energy, there are very limited areas and devices to trap this energy.
(v) To harness ocean thermal energy the difference in the temperature of surface hot water and the cold water at depth must be 20oC or more.

3. What is geothermal energy?

Answer: Thermal energy produced and kept in the Earth is known as geothermal energy. It comes from beneath the earth’s crust in the form of steam.

4. What are the advantages of nuclear energy?

Answer: The benefits of nuclear energy include the fact that 

i. it releases millions of times more energy per unit mass than burning the same amount of coal.
ii. There is no smoke produced by it. This energy is clean.

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

Answer: Some energy sources, like solar cells and wind turbines, can be regarded as pollution-free because they don’t harm the environment when they’re in use, but the creation of the device would have had an impact.

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

Answer: Because hydrogen produces water when it burns or is in combustion, it is a cleaner fuel than compressed natural gas (CNG), which contains methane and burns to produce carbon dioxide.

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

Answer: Solar energy and wind energy are the two energy sources that can be categorised as renewable energy sources.

i. Solar energy: Solar energy is sun-derived energy that can be used for heating, lighting, and cooking. Helium and hydrogen are abundant in the sun and could last for billions of years. As a result, solar energy is a sustainable form of energy.

ii. Wind energy: The windmill is used to capture wind energy and transform its kinetic energy into mechanical work or electricity. The difference in temperatures on the earth’s surface is what causes the wind to move. The sun, which will be around for billions of years, is what heats the earth. Consequently, wind energy can be regarded as a renewable energy source.

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

Answer: Two exhaustible sources of energy is as follows

i. Coal: It cannot be replenished quickly and is made from the dead remains of plants and animals that were buried under the earth’s crust millions of years ago. As a result, it is a finite source of power.

ii. Petroleum: Also known as crude oil or just oil, petroleum is a fossil fuel that was created millions of years ago from the remains of extinct marine organisms and cannot be replenished quickly. As a result, it is a finite source of power.


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

Answer: (B) a cloudy day.

2. Which of the following is not an example of a biomass energy source?

Answer: (C) coal

3. Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?

Answer: (C) nuclear energy

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

Answer: All of the earth’s life depends primarily on the sun for its energy. Even fossil fuels contain energy that is derived from the sun. Food is prepared by green plants by converting solar energy into chemical energy, which is then stored as biomass. Animals receive the same biomass as humans. Thus, the biomass that is stored as energy in fossil fuels has its source in the sun.

5. Compare and contrast biomass and hydroelectricity as sources of energy.

Answer: Energy from biomass is produced by the decomposition of agricultural waste, whereas hydroelectricity is produced using the kinetic energy of moving water. Because biomass is made up of organic substances, the energy produced by biomass causes air pollution. On the other hand, hydroelectricity produces no pollution.

6. What are the limitations of extracting energy from— (a) the wind? (b) waves? (c) tides?

Answer: (A) Wind that blows fast enough isn’t always and everywhere available. Wind is not a reliable source of energy as a result. Only at the location of the windmill can wind kinetic energy, also known as wind energy, be used.

(b) Only areas with powerful waves could use wave energy for commercial purposes. In order for wave energy to be used, it must first be transmitted over great distances.

(c) There aren’t many locations that are suitable for capturing tidal energy. The amount of water that rises and falls during tides is not very large. Therefore, it is not feasible to produce electricity on a large scale.

7. 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?

Answer: The options in (a) and (b) are similar. Renewable energy sources, also known as inexhaustible energy sources, are those that can be produced by humans, are continuously produced by natural processes, or have an endless supply. On the other hand, non-renewable or exhaustible sources of energy are those that cannot be replenished in the near future.

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

Answer: Following are the qualities of an ideal source of energy:

  • It should do a large amount of work per unit volume or mass.
  • Which would be easily accessible.
  • Which would be easy to store and transport.
  • Be economical.

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

Answer: The advantages of the solar cooker are:

(i) The cost of making such a cooker is very less.
(ii) The food never gets burnt in this type of cooker and stays hot.

The disadvantages of the solar cooker are:

(i) This type of cooker cannot be used for frying or preparing chapatis.
(ii) This device cannot be used at night for preparing food. 

10. Why is biogas plant a safe and efficient method of waste disposal? Justify.

Answer: Every organic waste, including cow manure, plant waste, and crop residue, is used in a biogas plant as a fuel to create biogas. Kitchen wastes and other waste products are also used. Therefore, all waste is disposed of and turned into biogas.

11. Construction of dams submerges large areas of forests, how does this contribute to the greenhouse effect?

Answer: Large tracts of forests are submerged when dams are constructed. When this submerged vegetation engages in anaerobic respiration, it releases greenhouse gases like methane and CO2. As a result, it influences the greenhouse effect.

12. What is a dam? Why do we seek to build large dams? While building large dams, which three main problems should particularly be addressed to maintain peace among local people? Mention them. 

Answer: A dam is a physical obstruction that stores, halts, and controls the flow of water. Large dams are constructed to store a lot of water. To keep the peace among the locals, it is especially important to address the following three issues: 

  • They should be compensated for lost property.
  • They should guarantee that new shelter will be provided.
  • Land for farming should be provided for them.

13. Increasing demand of fossil fuels has caused harm to our environment. List its three ill-effects. Suggest three measures to reduce the consumption of fossil fuels.

Answer: The following are the three negative effects of burning fossil fuels:

i. Global warming
ii. Air pollution
iii. Acid rain

The following are the three measures to reduce the use of fossil fuels:

i. Using clean fuels, such as CNG and LPG.
ii. Choosing not to drive a personal vehicle.
iii. Making use of renewable energy sources.

14. A group of farmers teamed together to set-up a biogas plant close to their farms. List any six advantages that they would be able to derive from the plant.

Answer: They would be able to benefit from the plant in six different ways.

(i) Farms’ disposal of waste.
(ii) Effective removal of animal waste.
(iii) Biogas used in chulhas as fuel.
(iv) Farmland manure.
(v) Using biogas to light homes.
(vi) Financial advantages.

15. What do you suggest to overcome the problem of “limitation of sources of energy”? Mention any three suggestions for the effective use of energy.

Answer: By wisely using the finite sources of energy, we can solve the “limitation of sources of energy” issue. The following are three ideas for efficient energy use:

i. Shutting off lights and other appliances when not in use.
ii. Switch out our incandescent bulbs for energy-efficient ones.
iii. Increase our use of renewable energy sources.

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

Answer: Following are some negative effects of rising energy demand on the environment:

i. Using fossil fuels more frequently results in more air pollution, which is bad for our health.
ii. Global warming, which is a result of the greenhouse effect, is causing odd changes in weather patterns all over the world. 

Steps to reduce energy consumption:

i. When possible, commute by bicycle or take public transportation instead of a private vehicle.
ii. Refrain from wasting energy by not using modern technology when it is not necessary.
iii. Using cleaner, more environmentally friendly energy sources like solar and wind energy.

Tick (✓) the correct option

1. Choose the only renewable source of energy from the following:

Answer: (b) geothermal power

2. Which of the following is not fossil fuel?

Answer: (d) wood

3. Which of the following is not obtained from the destructive distillation of food?

Answer: (a) coal

4. The average amount of energy released during the fission of uranium atom is:

Answer: (d) 200 MeV

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