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NCERT Solutions for Class 10 Science Chapter 14 Sources of Energy

Candidates looking for the NCERT solution for Chapter 14, Sources of Energy in class 10 science, may use this article as a guide. This article has been prepared with lots of attention. In addition to assisting learners in earning a high grade on the board test, solving NCERT questions of class 10 physics, sources of energy also aids in passing competitive exams. Therefore, applicants can scroll down to get the NCERT Solutions For Class 10 Science Chapter 14 if they want to do well in the sources of energy unit of the class 10 science exam.

NCERT Solutions for Class 10 Science Chapter 14 Sources of Energy

NCERT Solutions for Class 10 Science Chapter 14 Inside Chapter Questions

Page Number: 243

Question 1:

What is a good source of energy?


A good energy source can supply adequate, secure energy at a constant rate for a considerable time.

Criteria of a good energy source are as follows:

  1. Per mass unit, it produces a lot of heat.
  2. Per mass unit, it accomplishes a tremendous amount of work.
  3. It is simple to get to.
  4. It is simple to transport and store.
  5. It is cost-effective.
  6. There is less smoke produced.

As a result, energy plays a crucial role in our daily lives.

Question 2:

What is a good fuel?


Write any three characteristics of a good fuel.


A good fuel has the following characteristics:

  1. It needs to be reasonably priced.
  2. It needs to be accessible.
  3. Its ignition temperature must be significantly higher than the normal temperature.
  4. It should be easy to transport and manage.
  5. When burned, it shouldn't release any hazardous byproducts.
  6. Its combustion rate ought to be predictable and constant.
  7. After burning, it shouldn't leave behind any ash or residue.
  8. Good fuel should have a high calorific value, producing more heat with less fuel.

Question 3:

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


I would want to use LPG-type cooking gas. Many of the requirements for a suitable fuel are met by it, including low ignition temperature, high calorific value, and non-polluting qualities.

Page Number: 248

Question 1:

What are the disadvantages of fossil fuels?


The following are the disadvantages of fossil fuels:

  1. The combustion of fossil fuels results in significant carbon dioxide production, which increases the greenhouse effect.
  2. Smoke from burning fossil fuels, such as coal, pollutes the air.
  3. The combustion of fossil fuels results in the production of acidic gases, including nitrogen oxide and sulfur dioxide. The acid rain impacts the water and soil resources by the acidic gases produced.
  4. We can't replenish fossil fuels quickly because they take millions of years to develop.

Question 2:

Why are we looking at alternate sources of energy?


Renewable Energy:

  1. Energy produced through natural processes and constantly replenished is known as renewable energy.
  2. Those forms of energy that can never run out are referred to as renewable energies.
  3. Examples include hydropower, geothermal, wind, and solar energy.

Non-renewable Energy:

  1. Non-renewable energy originates from sources that will deplete or won't be replaced in our lifetimes, according to number one.
  2. Fossil fuels, such as coal, oil, and natural gas, are some examples of non-renewable energy.

We are looking at alternate sources of energy because of the following reasons:

  1. Fossil fuels are non-renewable source of energy.
  2. They cannot be replaced and are not widely available.
  3. If fossil fuel consumption is not controlled, it will run out.

Question 3:

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


Use of Wind:

  1. In the past, the wind propelled boats and ships in the rivers and oceans.
  2. Additionally, the wind was utilized for grain milling and wind-powered water pumps.
  3. So, in the past, windmills used wind energy to do mechanical tasks like lifting/drawing water from wells.
  4. Electricity is produced today using windmills.
  5. The wind's kinetic energy is captured and transformed into electricity in windmills.
  6. Even today, sailing and the production of mechanical power employ the wind.


  1. Since ancient times, water has been utilized for drinking, bathing, cooking, washing, and many other domestic tasks.
  2. Water is now moved through pipes, canals, and pumping stations for use by the general population.
  3. A significant amount of water is also used in agriculture.
  4. Hydroelectric power can be produced when dams are built to provide electricity today.
  5. Potential energy from waterfalls is exploited as a source, and with the use of turbines, this energy is transformed into electricity.
  6. Water is also employed in industrial processes in large quantities.

Page Number: 253

Question 1:

What kind of mirror-concave, convex or plane - would be the best suited for use in a solar cooker? Why?


A concave mirror would be best suited in a solar cooker because it focuses the sunlight in a very small area of the solar cooker and a high temperature is produced in it which is sufficient to cook the food.

Question 2:

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


Tidal, wave and ocean thermal energy are several types of energy that can be derived from water.

  1. Tidal energy: A type of hydropower that uses water to transform tide energy into usable energy, such as electricity.
  2. Wave energy: An environmental friendly energy source derived from the waves' movement.
  3. Ocean thermal energy: Ocean thermal energy is the energy made accessible by the temperature difference between the ocean's surface and deeper layers of water.

Limitations of ocean energy harvesting:

  1. High construction costs for tidal power plants because they must be extremely durable to withstand the force of the water.
  2. The temperature differential between the water at the top, which is hot, and the water at the depth, which is cold, must be at least 200 C or more.
  3. A detrimental effect on aquatic life.
  4. Restrictions brought on by the location because there are few sites with high enough tidal ranges or flow rates. To generate electricity from wave energy, extremely powerful waves are needed.
  5. The relative positions of the Earth, moon, and Sun determine the amount of tidal energy.
  6. The fluctuating strength of ocean waves.

Question 3:

What is geothermal energy?


Geothermal Energy: Geothermal energy is heat-based energy kept in the earth's hot zones. Hot spots beneath the earth's crust where upward-moving magma collects due to geological changes. Steam is produced when the hot regions touch the underground water. Through the use of pipes and turbines, this steam is used to produce energy. There are occasions when hot water from the hot spot escapes to the surface. Hot springs are the name for these outlets.

Question 4:

What are the advantages of nuclear energy?


The advantages of nuclear energy are:

  1. It uses a very tiny amount of nuclear fuel to produce useful energy (like uranium-235).
  2. A nuclear power plant may continuously produce electricity for two to three years once nuclear fuel, such as uranium-235, is fed into the reactor. Repeatedly inserting nuclear fuel is not necessary.
  3. It does not create gases that contribute to the greenhouse effect, such as carbon dioxide, or that cause acid rain, such as sulphur dioxide.

Page Number: 253

Question 1:

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


There is no clean energy available. Every energy source emits some pollution. For instance, nuclear reaction byproducts are extremely hazardous to the environment.

Question 2:

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


Compared to compressed natural gas, hydrogen gas is cleaner. This is a result of the hydrocarbons in CNG.

In CNG, carbon plays the role of a contaminant. However, hydrogen is waste-free, and fusing hydrogen does not result in waste. Therefore, hydrogen is a cleaner option for rocket fuel than CNG.

Hydrogen as Rocket Fuel:

When burned with oxygen, hydrogen fuel emits no emissions. The fuel cell may operate at up to 80% efficiency when fuelled by pure hydrogen. In other words, electricity is created from 80% of hydrogen's energy. As a result, the efficiency of creating electricity is 80%, and the efficiency of converting it to mechanical power is 80%.

Page Number: 243

Question 1:

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


Renewable Energy:

The energy produced by natural processes and constantly replenished is known as renewable energy. Solar energy, water, wind, tides, geothermal heat, and biomass are a few types of renewable energy.

We would categorize the following two energy sources as renewable:

1.) Solar Energy:

The sun's radiant heat and light energy are collected using solar collectors.

They include photovoltaics, concentrator photovoltaics, artificial photosynthesis, solar heating, concentrated solar power (CSP), solar architecture, and photovoltaics.

Then, electricity is produced from solar energy in various ways, such as heat and light.

2.) Wind Energy:

We get our energy from the wind, which is called wind energy

Wind energy is created using big, towering wind turbines.

The natural airflow over the earth's surface drives the wind turbines. For this purpose, groundwater has been pumped out using windmills for hundreds of years.

Question 2:

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


Fossil Fuels:

  1. The decomposition of living things yields fossil fuels. The Earth's crust contains these fuels made of carbon and hydrogen.
  2. This fuel includes coal, petroleum, and natural gas, for instance.
  3. They are today the main source of energy on the globe. They pollute the air and are exhaustible (limited in number).
  4. Both fossil fuels, coal and wood, are limited energy sources due to the limited number of reserves available.
  5. These non-renewable energy sources include fossil fuels. We must thus defend them.


  1. It is composed of the lifeless remains of plants and animals that have been dormant beneath the surface of the earth for millions of years.
  2. Millions of years go into the formation of coal. Industrialization has boosted the demand for coal.
  3. On the other hand, coal takes longer to replace itself.
  4. It is, therefore, a nonrenewable or limited source of energy.


  1. Petroleum is a mixture of several distinct hydrocarbons and is a dark-coloured liquid fossil fuel. It is highly viscous. It is a very practical source of power.
  2. On the other hand, the petroleum extracted from oil wells can only be used after a while. It is called crude oil because it is impure.
  3. Distinct hydrocarbons separate to create different fractions during the fractional distillation process, which is used to refine this crude oil.
  4. Diesel, paraffin, gasoline, and kerosene are a few of the fractions. Petrol is the fuel used in vehicles. Plastics, tyres, and synthetic materials like polyester are the items made from the fractions left over after refining crude oil. It provides reliable, movable power.

Wood is a nonrenewable energy source as a result. Therefore, coal and wood are two energy sources that we consider exhaustible.

NCERT Solutions for Class 10 Science Chapter 14 Textbook Chapter End Questions

Question 1:

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

  1. a sunny day
  2. a cloudy day
  3. a hot day
  4. a windy day


b.) A cloudy day


Explanation for the Correct Option (b):

  1. The energy we derive from the sun is referred to as solar energy.
  2. The solar water heater is not heated by the sun's energy on cloudy days.
  3. As a result, the heater won't receive enough solar energy, and the water won't warm.
  4. Solar energy can be captured from the sun's radiation and transformed into heat or power.
  5. The first solar water heaters were just huge metal containers painted black since they are a good conductor of heat and can quickly warm up to high temperatures.
  6. Water in these containers heated up along with the container due to solar heat.
  7. Integrated Collector-Storage (ICS) systems, also known as batch collectors, heat water in opaque tanks or tubes inside an insulated box before storing it until it is needed. If family demand is minimal, water might stay in the collector for extended periods, becoming quite heated.
  8. Copper tubes are often attached to flat absorber plates to create flat-plate collectors. Inlet and outlet manifolds link a set of parallel tubes at either end to form the most typical design. The flat plate assembly is protected by tempered glass and housed in an insulated enclosure.
  9. Evacuated tube collectors are the most efficient collectors available. Each evacuated tube is similar to a thermos in principle. A glass or metal tube containing the water or heat transfer fluid is surrounded by a larger glass tube. The space between them is a vacuum, so very little heat is lost from the fluid.

Explanation for Incorrect Options:

Option (a):

  1. Sun radiation is used to produce solar energy.
  2. Heat or electricity can be produced using solar energy.
  3. So we can use a solar heater to get hot water on a sunny day.

Hence option A is incorrect.

Option (c):

  1. We receive sun rays on hot days from the sun, the primary energy source for solar heaters.
  2. As a result, the heater will receive enough solar energy to warm the water.
  3. So that on a hot day, we can utilize a solar heater.

Hence option C is incorrect.

Option D:

  1. Even on gloomy days, we can still feel the sun's heat radiation, but it's insufficient to warm the water.
  2. Solar water heaters can only be utilized when sunlight is present.
  3. As a result, heat radiation from the sun enters the solar heater, allowing us to use it to heat water.

Hence option D is incorrect.

Thus,Option (b) is the correct answer.

Question 2:

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

  1. Wood
  2. Gobar gas
  3. Nuclear energy
  4. Coal


c.) Nuclear energy.


Explanation of the Correct Option (c):

  1. Animal and plant waste is the basis of the renewable energy source known as biomass. Nuclear fission and fusion reactions release nuclear energy.
  2. Nuclear energy cannot be categorized as a bio-mass energy source. Atomic fusion and fission unleash enormous amounts of energy, known as nuclear energy.
  3. Nuclear fusion and fission can both occur in the absence of sunshine. Consequently, nuclear energy is not a kind of bio energy.

Explanation for the Incorrect Options:

Option (b):

  1. Burning wood is the most typical way that energy from solid fuel biomass is used.
  2. Other exciting atoms heat the log when burning wood, releasing its stored potential energy.

Option (b):

  1. Since biomass is used to transform biogas through anaerobic digestion into a more useful and lucrative fuel, biogas is categorized as a secondary energy source.
  2. Biogas, produced from plant and animal waste, is also known as gobar gas.

Option (d):

  1. Because coal is produced from once-living plants, it is referred to as a fossil fuel.
  2. Because coal is made from plants, and plants derive their energy from the sun, coal also contains solar energy.

Thus, the correct option is (c).

Question 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?

  1. Geothermal energy
  2. Wind energy
  3. Nuclear energy
  4. Biomass


c.) Nuclear energy.


Explanation for the Correct Option (c):

  1. Energy is released during nuclear processes either through fission or fusion. Nuclear fission is splitting atoms to produce smaller atoms while releasing energy. In nuclear fusion, smaller atoms combine to form a larger atom.
  2. Nuclear power plants derive their energy from nuclear fission.
  3. Even without sunshine, nuclear reactions can produce vast amounts of energy.

Explanation of the Incorrect Options:

Option (a):

  1. Geothermal energy is the name for the earth's heat.
  2. The word "geothermal" comes from the Greek words "geo" (earth) and "therme" (heat). Geothermal energy is a renewable energy source because heat is continuously produced deep within the earth.
  3. Geothermal energy is utilized to create power, heat structures, and give people access to hot water.

Option (b):

  1. Wind energy is utilized to generate electricity by utilizing the kinetic energy offered by flowing air.
  2. This is transformed into electrical energy using wind turbines or other wind energy conversion technology. The turbine attached to the blades of a wind turbine is turned by the wind that reaches them first.

Option (d):

  1. Biomass is made up of resources derived from living creatures like plants and animals because it is organic.
  2. The sources of biomass are what they are. Plant, wood, and trash are the most common types of biomass materials utilized for energy. It is feasible to use biomass as a non-renewable energy source.

Thus, the correct answer is Option (c).

Question 4:

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


Fossil Fuels:

  1. Fossil fuels are fuels created by natural processes like decomposing extinct and buried organisms.
  2. Fossil fuels are flammable geologic deposits of organic matter, such as dead plants and animals, found beneath several thousand feet of sediment.
  3. These deposits gradually deteriorated over time and were finally converted into natural gas, coal, and petroleum due to the extreme heat and pressure inside the earth's crust.

Solar Energy:

  1. The conversion of solar energy makes solar energy one of the renewable energy sources.
  2. When sunlight enters the planet's atmosphere, most of its energy is converted to visible light and infrared radiation.
  3. Plants use the process of photosynthesis to convert this energy into sugar and carbohydrates.
  4. Solar cell panels are used to convert these energies into electrical energy.

Advantages of Fossil Fuels and Solar Energy:

Fossil Fuels Solar Energy
i.) Fossil fuels can generate a lot of power at one time. It is regarded as the cleanest form of energy since, unlike fossil fuels, it doesn't emit carbon dioxide, one of the reasons contributing to global warming.
ii.) They are really easy to find. Because it is simple to capture, free energy.
iii.) They are economically important. Savings on utility costs.
iv.) Transporting gas and oil is easy through pipes. Because the energy might be kept in the batteries, dependability is not an issue.
v.) Despite being a finite resource, it is abundant. The sun will always provide enough energy for the planet.

Difference Between Fossil Fuels and Solar Energy:

Fossil Fuels Solar Energy
i.) Carbon dioxide, a substantial greenhouse gas and the primary pollutant, is released when fossil fuels are burned. This has contributed to global warming. Wintertime and cloudy days have reduced production rates.
ii.) They are a non-renewable resource, which means that once they are used up, they cannot be regenerated. The installation as well as the initial cost of the components are expensive.
iii.) The environment becomes increasingly acidic as a result of the use of fossil fuels. This has caused unexpected and harmful alterations in the ecology. More space is being taken up.

Question 5:

Compare and contrast biomass and hydro-electricity as sources of energy.


  1. Hydroelectricity and biomass, both are examples of renewable energy sources.
  2. While using hydroelectricity does not produce any pollutants, burning biomass produces air pollution.
  3. While hydroelectricity can only be generated through the construction of hydro-power plants, biomass energy can be generated without using any particular equipment.

Question 6:

What are the limitations of extracting energy from

  1. the wind?
  2. waves?
  3. tides?


a.) Limitations of Wind Energy:

  1. It is not possible to build wind farms everywhere. Only in locations where the wind blows for the majority of the year can wind farms be built.
  2. To maintain the necessary output level, the wind needed for energy production must be strong and consistent. A wind speed of at least 15 km/h is required for the wind generator to operate effectively. That is only sometimes the case.
  3. Wind energy farms need a sizable amount of land.
  4. It is exceedingly expensive to build up wind energy plants.

b.) Limitations of Wave Energy:

  1. Only in locations with extremely strong sea waves would it be possible to harness the energy of the waves. Time and geographical restrictions apply to this.

c.) Limitations of Tidal Energy :

  1. There aren't many locations in the world that are appropriate for constructing tidal dams.
  2. It is impossible to produce enough electricity on a big scale using the rise and fall of sea water caused by high and low tides.

Question 7:

On what basis would you classify energy sources as

  1. renewable and non-renewable?
  2. exhaustible and inexhaustible?

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


a.) Energy sources that can be recycled are referred to as renewable energy sources. In contrast, sources of energy that cannot be recycled are referred to as non-renewable sources.

Renewable energy sources include the sun (solar power), biomass, wind power, etc.

Sources that are not renewable: coal, petroleum, etc.

b) Energy sources that will run out shortly are exhaustible. In contrast, sources that won't run out or disappear for a while are referred to as inexhaustible energy sources.

Exhaustible resources: coal, oil, etc.

Renewable resources include the sun (solar energy), biomass, wind, and others.

Yes, both options (a) and (b) are very much same.

Question 8:

What are qualities of an ideal source of energy?


The qualities of an ideal energy source are:

  1. It must have the ability to produce enough usable energy.
  2. It should deliver a huge amount of energy per unit.
  3. Pollutants shouldn't be present there.
  4. It ought to be more affordable.
  5. It ought to be easy to use.
  6. It shouldn't produce a lot of smoke or odors.
  7. Both preserving and transporting it should be straightforward.
  8. It ought to be economical.

Question 9:

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


Advantages of using solar cooker:

  1. Utilizing a solar cooker to prepare meals reduces the need for expensive fuels like coal, kerosene, and LPG.
  2. Because solar cookers don't emit smoke, they don't contaminate the air.
  3. Food cooked in a solar cooker retains its nutritional value. This is because food is cooked at a somewhat lower temperature in a solar cooker.
  4. Up to four different foods can be cooked simultaneously with a solar cooker.

Disadvantages of using solar cooker:

  1. The solar cooker cannot be used to cook food at night because sunlight is not available then.
  2. If the day sky is covered with clouds, even then, solar cookers cannot be used to cook food.
  3. The direction of the reflector of the solar cooker has to be changed from time to time to keep it facing the sun.

Place where solar cookers have limited utility.

The box-style solar cooker cannot be used for frying or baking (such as for preparing chappattis, etc.). The solar cooker is only useful in locations where it rains for the majority of the year or where the sky is constantly clouded.

Question 10:

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


The following are a few environmental effects of the rising energy demand:

  1. Fossil fuel burning results in acid rain, which harms plants (crops), soil, and aquatic life.
  2. The atmospheric concentration of the greenhouse gas carbon dioxide is rising due to the burning of fossil fuels. Rainfall has also been impacted.
  3. Soil erosion and wildlife extinction result from cutting down forest trees for firewood.
  4. he natural balance is being upset by installing hydropower units.
  5. Radioactivity in the environment is rising due to nuclear power plants.

To cut back on energy use, take the following actions:

  1. Turn off lights, fans, TVs, and other electrical devices while not in use to conserve energy.
  2. To save power, use energy-efficient electrical appliances. To do this, tube lights and compact fluorescent lamps (CFLs) can be used instead of standard filament-type electric bulbs.
  3. High-quality stoves should be utilized to get the most heat possible when burning fuels like kerosene and LPG.
  4. To conserve fuel, food should be cooked in pressure cookers.
  5. When it's feasible, utilize solar cookers to prepare meals and solar water heaters to heat water.
  6. In rural regions, it should be promoted to use biogas as fuel.
  7. Bicycles should be used for short distances to save fuel like petrol used in cars, scooters, and motorcycles.

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