NCERT Solutions for Class 10 Science Chapter 14 Sources of Energy for SEBA/CBSE

Get free NCERT Solutions For Class 10 Science Chapter 14 Sources Of Energy. These solutions are also important for SEBA board or any state board that follows the NCERT Text books. Whether you are preparing for your school exams, board exams, or revising key concepts, these NCERT Solutions for Class 10 Science Chapter 14 Sources Of Energy will develop your understanding of the key concepts of the chapter. Each answer is explained in simple language to help you build a strong understanding of the chapter and score better in your upcoming HSLC examinations.

See More
NCERT Solutions for Class 10 Science Chapter 6 Life Processes
NCERT Solutions for Class 10 Science Chapter 5 Periodic Classification of Elements
NCERT Solutions For Class 10 Science Chapter 14 Sources Of Energy

Q1. What is a good source of energy?

Ans:

A good source of energy has the following properties:

• It should be affordable and cost-effective.
• It should be easy to store and transport.
• It should be readily available and accessible.
• It should release a large amount of heat per unit mass.

Q2. What is good fuel?

Ans:

A good fuel has the following properties:

• It should produce a lot of heat when a small amount burns.
• It should be cheap and easily available.
• It should be easy to store and transport.
• It should not produce any poisonous substances while burning.
• It should leave little or no ash or residue after burning.
• It should have a low ignition temperature. (It catches fire easily when needed, but it does not catch fire on its own at room temperature.)

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

Ans:

I would use LPG (Liquefied Petroleum Gas) for heating and cooking food. It is a good fuel because:

• It has a high calorific value and gives a lot of heat.
• It burns cleanly and produces very little smoke.
• It is easy to store, transport, and use at home.
• It causes very little pollution compared to fuels like wood or coal.
• It is highly inflammable.

NCERT Solutions for Class 10 Science Chapter 14 Page: 248

Q1. What are the disadvantages of fossil fuels?

Ans:

The following are the disadvantages of fossil fuels:

• Burning fossil fuels like coal and petroleum causes air pollution, as they release large amounts of pollutants.
• The burning of fossil fuels releases carbon dioxide, which increases global warming.
• Fossil fuels are non-renewable sources of energy.
• Fossil fuels release sulphur dioxide and nitrogen oxides, which cause acid rain. Acid rain damages soil, water resources, and living organisms.
• Fossil fuels cannot be replenished in a short time because it takes millions of years to form them.

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

Ans:

We are exploring alternate sources of energy because fossil fuels are non-renewable. They are not available in large quantities and cannot be replenished. Fossil fuels will get exhausted if their consumption is not controlled. Also, fossil fuels cause air pollution and global warming. Therefore, it is better to switch to an alternate source of energy like solar, wind, hydro energy, etc.

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

Ans:

Traditionally, wind energy was used through windmills to do simple mechanical work, like lifting water from a well or run a grain-grinding machine. However, nowadays, windmills are used to generate electricity. When wind blows, it turns the blades of the windmill. This rotates a turbine connected to a generator, which produces electricity.

In the past, people used the natural flow of waterfalls to get energy. But natural waterfalls are limited. So nowadays, we build dams to store water at a height. When this water is released, it flows down, and it rotates turbines connected to generators, which produces electricity.

NCERT Solutions for Class 10 Science Chapter 14 Page: 253

14.3 ALTERNATE OR NON-CONVENTIONAL SOURCE OF ENERGY

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

Ans:

A concave mirror is best suited for use in a solar cooker because it can focus sunlight to a single point called the focal point. When sunlight falls on a concave mirror, it converges at the focal point, which increases the intensity of the heat at that spot. This concentrates a large amount of heat energy at that one spot. This heat is then used to cook food more efficiently by raising the temperature significantly.

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

Ans:

The energy from the oceans can be obtained mainly in three forms. These are
(i) tidal energy
(ii) wave energy and
(iii) ocean thermal energy

Ocean energy has some limitations:

1. Tidal energy can be produced only at a few suitable locations where tidal dams can be built.
2. Wave energy requires strong and continuous ocean waves, which are not available everywhere.
3. Ocean thermal energy can be used only where the temperature difference between the warm surface water and the cold deep water is at least 20°C. Setting up such power plants is also costly.

Q3. What is geothermal energy?

Ans:

The energy obtained from the molten rocks in the deeper hot regions of earth’s crust is called geothermal energy. It is produced from hot spots beneath the Earth’s surface. When underground water comes into contact with these hot spots, it turns into steam. This steam is used to generate electricity in geothermal power plants.

Q4. What are the advantages of nuclear energy?

Ans:

The following are the advantages of nuclear energy:

1. It produces a very large amount of energy from a small amount of nuclear fuel.
2. Nuclear power plants can generate electricity continuously for a long time without frequent refuelling.
3. It does not produce harmful gases like carbon dioxide or sulphur dioxide during electricity generation, so it causes less air pollution.

Page Number: 253

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

Ans:

No source of energy is completely pollution-free. Every source of energy causes some environmental impact during its production, use, or disposal. For example, solar cells are considered to be pollution-free, but their manufacturing may cause pollution. Similarly, nuclear energy releases no emissions while generating electricity, but the fission process produces hazardous radioactive waste. Hence, no source of energy is pollution-free.

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

Answer:

Yes, hydrogen is a cleaner fuel than CNG. When hydrogen burns, it produces only water, whereas when CNG burns, it produces CO₂ and water. The carbon dioxide can produce the greenhouse effect in the atmosphere and global warming. Since hydrogen releases no harmful emissions, it is a cleaner fuel than CNG.

In-text Questions Page: 254

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

Answer:

Wind energy: Wind energy is obtained from the movement of air at high speed. Wind energy is trapped using windmills to generate electricity. Wind blows because of uneven heating of the Earth. Since the heating of the Earth will continue forever, wind energy will also be available forever. Hence, wind energy is a renewable source of energy.

Solar energy: The energy obtained from the Sun is called solar energy. The sun contains a huge amount of hydrogen. Solar energy is produced by the fusion of hydrogen into helium. The Sun is expected to continue shining for billions of years. Hence, solar energy is a renewable source of energy.

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

Answer

Fossil fuels like coal and petroleum are two exhaustible sources of energy. These fuels were formed millions of years ago. Their reserves are limited and take a very long time to form. If we continue to use them at present rates, these reserves will be exhausted soon.

Exercises Questions Page: 254

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

Q1. 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

Ans:
(b) A cloudy day.

Q2. Which of the following is not an example of a biomass energy source ?
(a) Wood
(b) Gobar gas
(c) Nuclear energy
(d) Coal

Ans:
(c) Nuclear energy.

Q3. 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 ?
(a) Geothermal energy
(b) Wind energy
(c) Nuclear energy
(d) Biomass

Ans:
(a) Geothermal energy.

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

Answer:

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

Ans:

Q6. What are the limitations of extracting energy from:
a. The wind?
b. Waves?
c. Tides?

Ans:

(a) Limitations of wind energy

• Wind energy farms cannot be set up everywhere; they need a location where wind blows for most of the year. A windmill requires a wind speed of more than 15 km/h to run the turbine to generate electricity.
• Wind energy farms requires large area of land.
• The initial cost of establishing wind energy farm is very high.
• A windmill needs a high level of maintenance.

(b) Limitations of wave energy : 

Wave energy can only be extracted at places where waves are very strong, so its use is limited to specific coastal areas.

(c) Limitations of tidal energy :

• There are very few suitable sites available for construction of dams.
• The construction of dams and power plants is expensive.

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) Renewable and non-renewable sources:

This is based on the ability of the source to regenerate or replenish in a short period.

Renewable Sources: Renewable energy sources are those which are continuously produced in nature and can be regenerated naturally, such as solar energy, wind energy, hydro energy and biomass.

Non-renewable: The sources of energy that will get depleted someday and cannot be regenerated quickly once used up are called non-renewable sources of energy. Examples: Coal, petroleum, natural gas, etc.

(b) Exhaustible and Inexhaustible Sources

This is based on whether an energy source gets exhausted on use or not.

• Exhaustible sources are those sources which are limited and may get depleted after continuous use, such as coal and petroleum. Inexhaustible sources are those sources which are available in unlimited quantities and do not get exhausted, such as solar energy and wind energy.

Yes, the classifications given in (a) and (b) are almost the thing. Renewable sources are the same as inexhaustible sources, and non-renewable sources are the same as exhaustible sources.

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

Ans:

The following are the qualities of an ideal source of energy:

• It should produce a large amount of energy per unit mass or volume.
• It should be affordable and economical to use.
• It should be easy to store and transport.
• It should be easily accessible.

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

Ans:

Advantages of a solar cooker:

• It uses solar energy, which is renewable, clean, and free of cost.
• It does not produce smoke or air pollution.
• It saves conventional fuels such as LPG, kerosene, and coal.

Disadvantages of a solar cooker:

• It cannot be used at night or during cloudy and rainy weather.
• Cooking takes more time than conventional methods.
• It is not suitable for frying or baking food.

Yes, solar cookers have limited utility in polar regions, high-latitude zones, and tropical areas that experience frequent rainfall or prolonged cloudy skies throughout the year, as they do not receive sufficient direct sunlight.

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

Ans:

The following are the consequences of using different sources of energy:

1. Use of fossil fuels causes air pollution and leads to problems like acid rain and releases greenhouse gases.
2. Excessive use of fossil fuels also releases carbon dioxide, which contributes to global warming.
3. Construction of dams may destroy large ecosystems and create problems related to the rehabilitation of displaced populations.
4. Construction of hydroelectric plants may affect marine ecosystems and aquatic animals.
5. Nuclear power plants produce radioactive waste, which can be harmful if not managed carefully.
6. Deforestation to get firewood leads to soil erosion and destroys the natural homes of wildlife.

Steps to reduce energy consumption:

1. Switch off lights, fans, and other electrical appliances when they are not in use.
2. Use energy-efficient devices, such as CFLs or LED lights.
3. Use pressure cookers, solar cookers and solar water heaters wherever possible.
4. Encourage the use of biogas as a fuel, especially in rural areas.
5. Use public transport, bicycles, etc. to reduce fuel consumption.