Coal and Petroleum Class 8 Extra Questions Science Chapter 5

Coal and Petroleum Class 8 Extra Questions Science Chapter 5

Q1. Name some renewable sources of energy.

Ans: Water, wind, solar etc.

Q2. What are renewable sources of energy?

Ans: Renewable sources of energy are those sources of energy that are known to be replenished by themselves.

Q3. What are non-renewable sources of energy? Give some examples.

Ans: A nonrenewable resource is a natural substance that is not replenished with the speed at which it is consumed. It is a finite resource. Example: coal, natural gas, oil, and nuclear energy.

Q4. Give some examples of fossil fuels.

Ans: Coal, petroleum, natural gas.

Q5. Name the elements present in coal.

Ans: Carbon, oxygen and sulphur.

Q6. Which are the two main techniques of mining?

Ans: Surface mining and underground mining.

Q7. List four varieties of coal.

Ans: Peat, lignite, bituminous, anthracite.

Q8. Name the process of conversion of wood into coal.

Ans: Carbonisation

Q9. Name the gas that occurs over petroleum in reservoirs deep inside the earth.

Ans: Natural gas

Q10. Name two fractions of petroleum which are used as fuel.

Ans: Petrol and diesel

Q11. What kind of pollution is caused by the burning of fossil fuels?

Ans: Air pollution

Q12. Write the full form of LPG.

Ans: Liquefied Petroleum Gas.

Q13. Which gas is produced when coal is burnt in air?

Ans: Carbon dioxide

Q14. What is the purest form of carbon?

Ans: Coke

Q15. What is fuel?

Ans: Anything that burns to produce energy in an efficient manner is called a fuel.

Q16. Define fossil fuels.

Ans: Natural fuels that are made up by burial of living organisms under deep down the earth for over a long period of time, are called fossil fuels.

Q17. What is coal? Write its two uses.

Ans: Coal is a hard, black combustible substance that mainly contains carbon.

The uses of coal are:

a) It is used as a fuel in homes and industry.

b) It is used as a fuel at Thermal Power Plants for generating electricity.

Q18. Name three constituents of petroleum and write their uses also.

Ans: The three constituents of petroleum are:

  • petrol
  • paraffin wax
  • diesel

Uses:

  • Petrol: It is used as a motor fuel and for dry cleaning.
  • Paraffin wax: It is used for making ointments, candles, vaseline, etc.
  • Diesel: It is used as a fuel for heavy motor vehicles and electric generators.

Q19. Name two products that you obtain from the destructive distillation of coal. What is the residue left in’ this process? Give one main use of this residue.

Ans: The two important products obtained from the destructive distillation of coal are: Coal gas and coal tar. The residue left in this process is coke. Coke is used mainly as a reducing agent in the extraction of metals.

Q20. Define the term ‘petrochemicals’.

Ans: Petrochemicals are the substances obtained from petroleum and natural gas. They are used in the manufacture of detergents, fibres, polythene, etc

Q21. Differentiate between coke and coal.
Answer:

CokeCoal
(i) It is an amorphous form of carbon.(i) It is a non-crystalline form of carbon.
(ii) It is obtained by heating soft coal in absence or limited supply of air.(ii) It is obtained by the decay of vegetation which existed millions of years ago.

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