Sources of Energy Chapter 6 D.A.V School Science

 A. Fill in the blanks.

1. Coal And petroleum are non-renewable sources of energy.

2. Solar energy is a major renewable, natural resource.

3. The process, in which coal is strongly heated in the absence of air, is known as destructive distillation.

4. In oil wells, natural gas is always found above the layer of petroleum.

5. Coal tar is a black viscous liquid, obtained by destructive distillation of coal.

B. State true or false for the following statements.

1. Fossil fuels are renewable natural resources.

Ans- False

2. Anthracite has higher carbon content than lignite.

Ans- True

3. Coke can be used to make fuel gases.

Ans- True

4. Natural gas is found below the petroleum layers.

Ans- False

5. Burning of fossil fuels is a major source of pollution.

Ans- True

C. Tick the correct option.

1. The highest grade of coal is known as----

Ans- Anthracite

2. Coke and coal tar are obtained from----

Ans- Coal

3. Different type of coal generally have the----

Ans- Different content of volatile material as well as different percentage of carbon.

4. A product, that is not obtained through the refining of petroleum is----

Ans-  Coal gas

5. Which of the following is a renewable source of energy?

Ans- Tidal energy

D. Answer the following questions in brief

1. Define the term 'fuel'.

Ans- Any substance which produces heat and light on burning, is known as fuel.

2. Name two renewable natural sources of energy.

Ans- Wind energy and tidal energy are two renewable natural sources of energy.

3. Define the term 'Carbonisation'.

Ans- Formation of coal is known as 'Carbonisation'.

4. Name the three main products obtained from destructive distillation of coal.

Ans- The three main products obtained from destructive distillation of coal are:-

i) Coke

ii) Coal tar

iii) Coal gas

5. State two uses each of the following:

(a) Asphalt

Ans- i) For making roads.

        ii) Coating of the underside of the electric poles.

(b) Paraffin wax

Ans- i) Used for making vaselines.

        ii) Used for making candles.

6. Write the full form of CNG, LPG and PNG.

Ans- The full form of CNG, LPG and PNG are:-

CNG- Compressed Natural Gas

LPG- Liquified Petroleum Gas

PNG- Piped Natural Gas

E. Answer the following questions.

1. Describe, in brief, the process of 'Coal formation'.

Ans- The remains of dead plants buried deep inside the earth, faces the action of heat from the earth core and the pressure of rocks over a long period of time, it gets converted into coal.

2. Differentiate between lignite and bituminous coal.

Ans- Lignite- i) It contains 38% of carbon.

                     ii) It is mainly used for power generation.

Bituminous- i) It contains 65% of carbon.

                     ii) It is used for power generation and for making coke.

3. How do petroleum and natural gas occur in nature?

Ans- Petroleum occurs in the rock formations as crude oil.

Natural gas is found in oil wells above the crude oil.

4. State the main advantages of using natural gas.

Ans-  Main advantages of using natural gas are:-

i) It is a clean fuel.

ii) It has a high calorific value.

iii) Natural gas is economical than petrol and diesel.

iv) It is easy to transport natural gas through pipelines.

5. Keeping in mind their availability in nature, explain the need of using coal and petroleum judiciously?

Ans- Coal, and Petroleum are non-renewable resources because it takes a long period of time to replenish it. Therefore, we should use alternative sources of energy like solar energy, wind energy, hydro energy, tidal energy, etc. Hence, their stock is going to be finished in near future.