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Let Us Exercise

1. Choose the correct option.

a. Which option correctly classifies a natural resource?
i. Soil – Exhaustible
ii. Natural gas – Inexhaustible
iii. Coal – Exhaustible
iv. Water – Exhaustible
 Answer: iii. Coal – Exhaustible

b. Which variety of coal is used as a fuel in the electric power station?
i. Bituminous coal
ii. Peat
iii. Anthracite
iv. Lignite
 Answer: iv. Lignite

c. Which petroleum product is used to manufacture cosmetics and shoe polishes?
i. Paraffin wax
ii. Naphtha
iii. Kerosene
iv. Gasoline
 Answer: i. Paraffin wax

d. Burning fossil fuels increases the concentration of greenhouse gases, leading to global warming. Which of the following is not a greenhouse gas?
i. Methane
ii. Carbon dioxide
iii. Nitrogen
iv. Water vapour
 Answer: iii. Nitrogen

2. Assertion–Reason Questions

(i) Assertion (A): Fossil fuels are exhaustible sources of energy.
Reason (R): Conversion of buried remains of plants and animals into fossil fuels takes place over millions of years.
Answer: Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
(Option a)

(ii) Assertion (A): Carbon monoxide is a highly poisonous gas.
Reason (R): Carbon monoxide is released during the complete combustion of fossil fuels.
Answer: Assertion (A) is true, but Reason (R) is false.
(Option c)

3. Answer the following questions in one sentence.

a. Which natural resource was formerly used for street lighting?
Coal gas was formerly used for street lighting before the invention of electricity. It was produced by heating coal in the absence of air and was stored in large gas lamps for lighting streets and houses.

b. What is carbonisation?
Carbonisation is the process by which the remains of dead plants buried under the earth for millions of years get converted into coal due to high temperature and pressure. It is a slow, natural chemical process.

c. What do you understand by refining of petroleum?
Refining of petroleum is the process of separating crude oil into different useful components or fractions such as petrol, diesel, kerosene, and LPG. It is done in oil refineries through fractional distillation.

d. What does PCRA stand for?
PCRA stands for Petroleum Conservation Research Association. It is an organisation that creates awareness about saving petroleum products, promotes energy conservation, and suggests ways to reduce fuel wastage in daily life and industries.

4. Answer the following questions in 2-3 sentences

a. On what basis are the components of petroleum separated in this process? Which component of petroleum is used in surfacing of tar roads?
The components of petroleum are separated on the basis of their different boiling points through fractional distillation. Each fraction is collected separately at different levels of the refinery. Bitumen, one of the heavy fractions, is used for surfacing roads.

b. Mention the adverse effects of acid rain.

Acid rain damages crops and forests, corrodes buildings, monuments, and bridges, and pollutes soil and water bodies. It also harms aquatic animals and affects human health indirectly. The main cause of acid rain is the burning of fossil fuels releasing harmful gases.

5. Answer the following questions 3-4 sentences

a. Mention the uses of natural gas.

Natural gas is a clean and efficient fuel used for cooking, heating, and generating electricity. It is also used in vehicles as CNG (Compressed Natural Gas). Industries use it as a raw material to produce fertilizers, chemicals, and hydrogen. Since it burns without smoke, it helps reduce air pollution.

b. What steps can be taken to reduce the use of fossil fuels?

We can reduce the use of fossil fuels by using public transport, carpooling, and switching to renewable energy sources like solar and wind power. People should conserve electricity, use energy-efficient appliances, and plant more trees. Industries should adopt eco-friendly technologies to reduce dependence on fossil fuels and protect the environment.