CBSE Class 8 Science Coal and Petroleum VBQs

Fill in the blanks.

(a) Fossil fuels Coal, Petroleum, and natural gas.

(b) Process of separation of different constituents from petroleum is called refining.

(c) Least polluting fuel for vehicle is Compressed Natural Gas (CNG).

Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory.
Answer : False

(b) CNG is more polluting fuel than petrol. 
Answer : False

(c) Coke is almost pure form of carbon.
Answer : True

(d) Coal tar is a mixture of various substances.
Answer : True

(e) Kerosene is not a fossil fuel. 
Answer : False

Very Short Answer type Questions

Question. Name the petroleum product used for surfacing of roads.
Answer : Bitumen.

Question. Explain the process of formation of petroleum.
Answer : Dead organisms that got buried in the sea millions of years ago got covered with layers of sand and clay. Due to lack of air, high temperature, and high pressure, these dead organisms got transformed into petroleum and natural gas.

Question. Describe how coal is formed from dead vegetation. What is this process called?
Answer : Dense forests got buried under the soil due to natural processes, millions of years ago. More and more soil got deposited over them and they got compressed more. This led them to get exposed to very high temperature and pressure. They slowly got converted into coal under these extreme conditions. The whole process of formation of coal from dead vegetation is known as carbonization.

Question. The following Table shows the total power shortage in India from 1991–1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

Answer :

Question. What are the advantages of using CNG and LPG as fuels?
Answer : The advantages of using compressed natural gas (CNG) and liquefied petroleum gas (LPG) as fuels are:
(i) They can be burnt directly.
(ii) They can be transported easily through pipe lines.
(iii) They are clean fuels and do not give smoke when burnt.
(iv) They give a lot of heat energy when burnt.

Question- Explain why fossil fuels are exhaustible natural resources.
Answer : Because sources of fossil fuels are limited on earth, and fossil fuels take million years to replenish.

Question. Write various constituents of petroleum and their uses.
Answer :

Question. Describe characteristics and uses of coke.
Answer : Characteristics: i) Coke is tough, porous and black in colour.
Uses: i) In the manufacture of steel, ii) In the extraction of metals (as a reducing agent).