NCERT Solutions for Class 8 Science Chapter 3 - Coal and Petroleum

NCERT TEXTBOOK QUESTIONS SOLVED
 

Q. 1. What are the advantages of using CNG and LPG as fuels?
Ans. The advantages of using CNG and LPG:
(i) CNG and LPG are clean fuels.
(ii) Their cost is low.
(iii) They can be used directly for burning.
(iv) They are easily available.
(v) They do not produce pollution.

Q. 2. Name the petroleum product used for surfacing of roads.
Ans. Bitumen is the petroleum product which is used for surfacing of roads these days.

Q. 3. Describe how coal is formed from dead vegetation. What is this process called?
Ans. About 300 million years ago, the earth had dense forests in low-lying wetland areas. Due to various natural processes, like floods and earthquakes, these forests got buried under the soil. The soil deposited layer by layer over them, they were compressed. Under high temperature and pressure, the plants got converted to coal slowly. This process is called carbonisation.

Q. 4. Fill in the blanks. (a) Fossil fuels are ______ , ______ and ______.
(b) Process of separation of different constituents from petroleum is called ______.
(c) Least polluting fuel for vehicles is ______.
Ans. (a) Coal, Petroleum and Natural gas
(b) Refining
(c) Compressed Natural Gas (CNG).
 

Q. 5. Tick True/False against the following statements.
(a) Fossil fuels can be made in the laboratory.
(b) CNG is more polluting fuel than petrol.
(c) Coke is almost pure form of carbon.
(d) Coal tar is a mixture of various substances.
(e) Kerosene is not a fossil fuel.     
Ans. (a) False (b) False
(c) True (d) True (e) False.
 

Q. 6. Explain why fossil fuels are exhaustible natural resources.
Ans. Fossil fuels are present in limited quantity in the nature. They can be exhausted by human activities. So fossil fuels are called exhaustible natural resources.

Q. 7. Describe characteristics and uses of coke.
Ans. Characteristics of coke:
(i) Coke is tough.
(ii) It is porous and black substance.
(iii) It is an almost pure form of carbon.

Uses:    Coke is used in the manufacture of steel and in the extraction of many metals.

Q. 8. Explain the process of formation of petroleum.
Ans. Petroleum is formed from organisms living in the sea. As the organisms died, their bodies settled at the bottom of the sea. These bodies got covered with layers of sand and clay. Over millions of years, in the absence of air, and under high temperature and pressure the dead bodies got converted into petroleum and natural gas.

Q. 9. 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 x-axis.

Ans. Scale: Along x‑axis 1 unit = 1 year
Along y ‑axis 1 unit = 1%