Most of the non-conventional sources of energy are ............... .
- exhaustible
- inexhaustible
- polluting
- derived from fossil fuels.
Answer
inexhaustible
Reason — Most non-conventional sources of energy, such as solar, wind, tidal, and geothermal energy, are inexhaustible because they are naturally replenished and do not get depleted with use.
Assertion (A): Solar energy is practically free.
Reason (R): Solar energy systems do not require a lot of maintenance.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R does not explain A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation — Solar energy is naturally available and solar energy systems do not require a lot of maintenance making it practically free.
Wind farms are rare in ............... .
- coastal regions
- open grasslands
- hilly regions
- river valleys.
Answer
river valleys.
Reason — Wind farms are usually installed in coastal regions, open grasslands or hilly regions where strong and steady winds are available; hence they are rare in river valleys.
Tidal energy can be harnessed at ............... .
- Gulf of Kutch
- Sunderbans
- Andaman and Nicobar Islands
- All of the above.
Answer
All of the above
Reason — In India, the prospective sites for exploitation of tidal energy are the Gulf of Kutch, Cambay and Sunderbans, while other suitable sites lie near the Lakshadweep Islands and the Andaman and Nicobar Islands; hence all the given locations are correct.
Geothermal energy is environment friendly.
- It has low emission of green house gases.
- It is independent of weather and season.
- It is easily accessible.
- It is independent of exchange rates.
Answer
It has low emission of green house gases.
Reason — Geothermal energy is environment-friendly because it has low emission of sulphur, carbon dioxide and other greenhouse gases; the other options are advantages of geothermal energy but do not relate to it being environment-friendly.
Assertion (A): Wind power accounts for nearly 10 percent of India's total installed power generation capacity.
Reason (R): Wind Mills can be installed in most regions — coastal regions, open grasslands or hilly regions.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R does not explain A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation — Wind Mills can be installed in most regions — coastal regions, open grasslands or hilly regions, due to which wind power accounts for nearly 10 percent of India's total installed power generation capacity.
The process of splitting of radioactive substances is called ............... .
- nuclear fission
- nuclear fusion
- nuclear reaction
- nuclear bombing
Answer
nuclear fission
Reason — When the atoms of radioactive substances react, they split apart, and this process of splitting of atoms is called nuclear fission.
Assertion (A): It is easy to harness the tidal energy.
Reason (R): Massive amounts of water in the oceans move in extremely predictable patterns.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R does not explain A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation — Massive amounts of water in the oceans move in extremely predictable patterns. This makes it easy to harness the tidal energy. Hence, Reason (R) correctly explains Assertion (A).
Which of the following is a green renewable automotive fuel?
- CNG
- CBG
- PNG
- Solar energy
Answer
CBG
Reason — Compressed Biogas (CBG) is purified biogas with a high methane content and high calorific value, which makes it a green, renewable automotive fuel; CNG and PNG are fossil-fuel based, and solar energy is not an automotive fuel.
Raghav's grandfather bequeathed a huge mansion in Rajasthan to Raghav. Which source of energy would you advise Raghav to use?
- Wind
- Solar
- Geothermal
- Biogas
Answer
Solar
Reason — Rajasthan receives an abundant amount of solar energy and enjoys a large number of clear sunny days, which is why the world's largest solar park, Bhadla Solar Park, is located in Jodhpur, Rajasthan.
Which of the following drawbacks of conventional sources of energy is forcing countries to shift to non-conventional sources of energy
- greenhouse gases emission
- fossil-fuel dependence
- non-renewable resources
- All of them.
Answer
All of them.
Reason — Conventional sources of energy emit greenhouse gases, depend largely on fossil fuels, and are non-renewable. These drawbacks are forcing countries to shift towards cleaner and renewable sources of energy.
Assertion (A): Nuclear energy is the most reliable source of energy.
Reason (R): Nuclear fuels are less affected by fluctuating fuel prices than the more volatile industries like oil and natural gas.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R does not explain A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true but R does not explain A.
Explanation — Nuclear energy is highly reliable because it provides a continuous supply of electricity throughout the year. Although nuclear fuel prices are more stable than oil and natural gas, this does not explain its reliability. Reliability refers more to the consistent output and availability of the energy source, not primarily to its price stability.
What are non-conventional sources of energy?
Answer
Non-Conventional sources of energy are those which have been developed in the recent past as an alternative to conventional sources of energy. These include solar energy, wind energy, tidal energy, geothermal energy, nuclear energy and biogas.
State two differences between conventional and non-conventional sources of energy.
Answer
| Conventional sources of energy | Non-Conventional sources of energy |
|---|---|
| Conventional sources of energy are those which have been used by man for a long time and are still being tapped and used abundantly. | Non-conventional sources of energy are those which have been developed in the recent past as an alternative to conventional sources of energy. |
| Except for hydel energy, these sources of energy are non-renewable. | Most of these sources are renewable. |
Give a reason for each of the following:
(i) Non-conventional sources of energy are called the resources of the future.
(ii) Solar energy is replacing fossil fuels in India.
(iii) Harvesting of solar energy does not require much maintenance.
Answer
(i) Non-conventional sources of energy are called the resources of the future as most of these sources of energy are renewable, non-polluting, less expensive to run and easy to maintain.
(ii) Solar energy is replacing fossil fuels in India because it is a renewable, inexhaustible and non-polluting source of energy, and India is favourably located to harness it, being on the Tropic of Cancer with about 300 clear sunny days in a year and receiving nearly 5,000 trillion kWh of solar energy annually. As solar energy saves fossil fuels like coal and petroleum and also reduces electricity bills, it is increasingly being used in place of fossil fuels.
(iii) Harvesting of solar energy does not require much maintenance as most reliable solar panel manufacturers give 20-25 years warranty. Also, as there are no moving parts, there is no wear and tear. So, after covering the initial cost of the solar energy system, it requires very little spending on maintenance and repair work.
How is India in an advantageous position to harness solar energy?
Answer
India is in an advantageous position to harness solar energy because of India's location on the Tropic of Cancer. Most parts of the country have 300 clear sunny days in a year and per hour per square km availability of solar energy between 5 to 7 kW.
The first half of this year (2025) saw something significant — for the first time ever, renewable energy eclipsed coal as the world's leading source of electricity, according to new data from the UK-based energy think tank Ember. India's grid has broadly mirrored this trend, with separate government data up to June 30 showing that non- fossil fuel sources in the country accounted for 50.1 per cent of its installed electricity capacity, displaced thermal. There sources — which include nuclear, large hydro, and renewables — made up just 30 per cent of installed capacity in India up to 2015 and 38 per cent in 2020, before surging sharply over the last five years, on the back of solar and wind power.
— Indian Express, 9 October, 2015
State briefly how the Sun's energy can be used to generate power.
Answer
Sun's energy can be transformed into electrical energy with the help of solar cells. Solar cells are also known as photovoltaic cells. They are made up of thin wafers of semi conductor materials from silicon and gallium. When Sun's light falls on them, the Sun's energy gets converted into electricity.
How can wind energy generate additional income for the land owners?
Answer
Land owners can look for additional income by installing wind turbines on land that can even be used for agricultural purposes. The electricity generated by wind power can be used for domestic consumption and reduce monthly electricity bills, and the surplus power can be sold back to the local grid which can result in more savings. Hence, wind energy can generate additional income for the land owners.
State any three advantages of using solar energy.
Answer
Three advantages of using solar energy are-
- It is a renewable source of energy which can be harnessed in most of the areas of the world.
- It can be used for diverse purposes like producing electricity in areas without access to the energy grid, to distill water in regions with limited clean water supplies and to power satellites in space.
- Solar energy systems do not require a lot of maintenance.
How is wind energy utilised to produce electricity?
Answer
The wind energy is obtained by making use of windmills. The blades of the windmill rotate due to the force of the wind. The rotational motion of the blades drives a number of machines like water pumps, flour mills and electric generators. A number of windmills are installed in a definite pattern in clusters called wind farms. They generate a large amount of electricity.
What is tidal energy? Give an advantage of using tidal energy.
Answer
The rise and fall of water of the ocean produced by the attraction of the Moon and Sun produces a large amount of energy called Tidal energy.
An advantage of Tidal energy is that it can be produced even if the water moves at a low speed.
Give two advantages of using wind energy.
Answer
Two advantages of using wind energy are-
- It is a renewable source of energy that can be produced again and again.
- It is the cleanest form of renewable energy that produces no pollution.
What are wind farms? Where are they usually located?
Answer
A number of windmills are installed in a definite pattern in clusters called wind farms.
They are usually installed in coastal regions, open grasslands or hilly regions.
(i) What is geothermal energy?
(ii) How is geothermal energy used to produce electricity?
Answer
(i) Geothermal energy is the heat energy contained in the rock and fluid that fills the fractures and pores within the rock in the earth's crust.
(ii) Geothermal energy is harnessed by drilling deep wells to tap underground hot water, steam, or hot rocks. The high-pressure steam drives a turbine connected to a generator to produce electricity. After use, the steam is cooled, condensed into water, and pumped back underground to be reused.
Name one area each where solar, wind, tidal and geothermal energy is generated in India.
Answer
| Energy | Area |
|---|---|
| Solar energy | Bhadla Solar Park, Jodhpur, Rajasthan |
| Wind energy | Madurai in Tamil Nadu |
| Tidal energy | Gulf of Kutch |
| Geothermal energy | Manikaran in Himachal Pradesh |
State any two advantages of using geothermal energy.
Answer
Two advantages of using geothermal energy are-
- It is easily accessible because of its extensive distribution.
- It is independent of weather and season.
Name the process involved in generation of nuclear energy. State any three advantages of using nuclear power.
Answer
The process involved in generation of nuclear energy is known as Nuclear Fission.
Three advantages of using nuclear power are —
- Nuclear energy reduces the requirement of the amount of energy generated from fossil fuels and therefore, reduces the use of fossil fuels and lowers Greenhouse Gas emissions.
- Fission of one atom of uranium produces ten million times the energy released by burning of one atom of carbon. In this way, nuclear energy not only saves on raw materials but also in transport, handling and extraction of nuclear fuel. The cost of nuclear fuel is 20% of the cost of energy generated.
- Nuclear energy is the most reliable source of energy as nuclear power plants can run 24 hours a day and seven days a week.
How is biogas beneficial for the farmers and householders?
Answer
Biogas is beneficial for the farmers in the form of energy and good quality manure. It is useful for the householders as the gas is used for cooking, lighting and pumping water from wells.
What is nuclear power?
Answer
Nuclear power is obtained from energy stored in the nuclei of atoms of naturally occurring radioactive elements like uranium, thorium and plutonium.
Name two minerals used for the generation of nuclear energy. Name two nuclear power plants in India.
Answer
Uranium and Thorium are the two minerals used for the generation of nuclear energy.
Two nuclear power plants in India are-
- Kaiga in Karnataka
- Kakrapar in Gujarat
Raw material for nuclear power are minerals that are non-renewable. But countries prefer it to conventional energy sources. Why?
Answer
Countries prefer nuclear power over conventional energy sources because it produces a large amount of energy from a small amount of fuel and does not emit harmful greenhouse gases. Even though the raw materials like uranium are non-renewable, nuclear power helps reduce air pollution and dependence on fossil fuels. It is a more efficient and cleaner energy option, making it attractive for meeting growing energy needs while protecting the environment.
Explain how using nuclear energy in a controlled environment can be a boon for our country.
Answer
Using nuclear energy in a controlled environment can be a boon for our country for the following reasons-
- Nuclear energy reduces the requirement of the amount of energy generated from fossil fuels and therefore, reduces the use of fossil fuels and lowers Greenhouse Gas emissions.
- Fission of one atom of uranium produces ten million times the energy released by burning of one atom of carbon. In this way, nuclear energy not only saves on raw materials but also in transport, handling and extraction of nuclear fuel. The cost of nuclear fuel is 20% of the cost of energy generated.
- Nuclear energy is the most reliable source of energy as nuclear power plants can run 24 hours a day and seven days a week. Besides, a nuclear plant needs to refuel every 18 to 24 months. This shows that nuclear fuels are less affected by fluctuating fuel prices than the more volatile industries like oil and natural gas.
- When compared to the fossil fuel waste, the nuclear waste which occurs due to the production of nuclear power is small in quantity.
Figure 1 is a picture of a biogas plant. Briefly explain how biogas is generated.
Answer
Biogas is produced by the anaerobic decomposition of animal and plant waste in the presence of water. In this oxygen-free environment, bacteria break down the waste and release methane-rich gas. The mixture is fed into an underground digester tank through an inlet pipe. As bacteria ferment the waste, biogas is collected through a gas outlet, while the leftover slurry is removed via an outlet pipe.
Name the main constituents of biogas.
Answer
The main constituents of Biogas are:
- Methane
- Carbon dioxide
- Hydrogen
- Hydrogen sulphide
List three advantages of biogas.
Answer
Three advantages of Biogas are as follows:
- Biogas is clean, non-polluting and cheap.
- There is direct supply of gas from the plant. Therefore, there is no storage problem.
- The sludge left behind is a rich fertiliser containing bacterial biomass.
Write a short note on Compressed Biogas.
Answer
Compressed Biogas (CBG) is purified biogas with over 90% methane, produced by removing hydrogen sulphide, carbon dioxide, and water vapour. Its high calorific value and properties make it a green, renewable automotive fuel. To promote CBG usage, blending it with CNG and PNG for households will be mandatory in phases from 2025–26. This initiative aims to boost domestic CBG production and reduce dependence on imported natural gas.
Observe Figure 2 and answer the following question:
(a) Identify the type of energy generated and state the advantages of using it.
(b) Which two areas can be well suited for its generation?
(c) Briefly describe the method of generating electricity by this method.
(d) In India this source of energy has been divided into provinces. Name three such provinces.
Answer
(a) The type of energy being generated in the given figure is Geothermal energy. The advantages of using Geothermal energy are as follows:
- It is easily accessible because of its extensive distribution.
- It is environment-friendly in nature; has low emission of sulphur, carbondioxide and other Greenhouse Gases.
- It is independent of external supply and demand effects and fluctuations in exchange rates.
- It is independent of weather and season.
(b) Two areas that can be well suited for its generation are - Manikaran in Himachal Pradesh, Puga Valley in Ladakh.
(c) Method of Generating Electricity Using Geothermal Energy is described below:
- Wells are drilled deep (thousands of feet) into the Earth to access hot water or steam from geothermal reservoirs.
- Hot water is pumped from deep underground through a well under high pressure.
- When the water reaches the surface, the pressure is dropped, which causes the water to turn into steam.
- The steam spins a turbine connected to a generator, producing electricity.
- After use, the steam is cooled in a cooling tower and condenses back into water.
- The cooled water is pumped back into the Earth to begin the process again.
(d) The names of three such provinces are as follows:
- Himalayan geothermal province
- Son-Narmada-Tapti graben
- Andaman-Nicobar Islands geothermal province.
Which non-conventional source of energy would you prefer to use for running street lights, water pumps for irrigation and heating your house? Give reasons to support your answer.
Answer
I would prefer solar energy for running street lights, water pumps for irrigation and heating my house because of the following reasons:
- Solar energy is a renewable source of energy which can be harnessed in most of the areas of the world.
- It can be used for diverse purposes - to produce electricity in areas without access to the energy grid, to distill water in regions with limited clean water supplies and to power satellites in space.
- Solar energy systems do not require a lot of maintenance. Most reliable solar panel manufacturers give 20-25 years warranty. Also, as there are no moving parts, there is no wear and tear. So, after covering the initial cost of the solar energy system, it requires little spending on maintenance and repair work.
- It saves fossil fuels like coal and petroleum, used to produce electricity and also reduces electricity bills.
More people in the rural areas are now opting for LPG cylinders for domestic cooking. Do you think LPG should be replaced by biogas? Give reasons to support your answer.
Answer
Yes, I believe that LPG should be replaced by biogas because of the following reasons:
- Renewable and sustainable — Biogas is produced from organic waste, making it a renewable energy source and reducing reliance on finite fossil fuels.
- Effective waste management — Biogas production helps in the decomposition of organic waste, offering an efficient waste management solution and reducing landfill waste.
- Lower emissions — Biogas emits fewer greenhouse gases and pollutants compared to LPG, leading to improved air quality and reduced environmental impact.
- Cost-effectiveness — In areas with abundant biomass waste, biogas production can be a cost-effective alternative, reducing the reliance on costly LPG cylinders.
- Energy independence — Biogas provides a decentralized energy source, promoting energy independence in rural areas by producing locally available biogas instead of relying on LPG cylinder refills.