Coal and Petroleum | Science 8th | Chapter 2

Science: Jammu and Kashmir | jandkncert |

Coal and Petroleum | Science 8th | Chapter 2 |

Q1. What are the advantages of using CNG and LPG as fuels?

Ans.

The advantages of using compressed natural gas (CNG) and liquified petroleum gas

(LPG) as fuels are:

(i) They can be burnt directly.

(ii) They can be transported easily through pipelines.

(iii) They are clean fuels and do not give smoke when burnt.

(iv) They give a lot of heat energy when burnt.

Q2. Name the petroleum product used for surfacing of roads.

Ans.

Bitumen, a petroleum product, is used for surfacing roads.

Q. Describe how coal is formed from dead vegetation. What is this process called?

Ans.

Millions of years ago, dense forests got buried under the soil due to natural processes like storms, floods, and earthquakes. These got compressed as more and more soil got deposited over them. When they got buried deep in the soil, they were exposed to very high pressure and temperature. Under these conditions, these slowly got converted into coal. This process of formation of coal from dead

vegetation is called carbonization.

Q3. Fill in the banks.

(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) Fossil fuels are coal, petroleum, and, natural gas.

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

(c) Least polluting fuel for vehicles is compressed natural gas (CNG).

Q5.Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory. (T / F)

(b) CNG is more polluting fuel than petrol. (T / F)

(c) Coke is an almost pure form of carbon. (T / F)

(d) Coal tar is a mixture of various substances. (T / F)

(e) Kerosene is not a fossil fuel. (T / F)

Ans.

(a) Fossil fuels can be made in the laboratory. (F)

(b) CNG is more polluting fuel than petrol. (F)

(c) Coke is an almost pure form of carbon. (T)

(d) Coal tar is a mixture of various substances. (T)

(e) Kerosene is not a fossil fuel. (F)

Q6. Explain why fossil fuels are exhaustible natural resources.

Ans. Fossil fuels require millions of years to form from the dead vegetation and animals that get buried deep inside the Earth. They require high temperature and pressure for their formation, which cannot be provided in the laboratory. Thus, fossils are limited. Therefore, the use of fossil fuels at this rate will lead to their exhaustion.

Q. Describe the characteristics and uses of coke.

Ans.

Characteristics of coke are:

(i) Tough

 (ii) Porous

(iii) Black in colour

Uses of coke:

(i) In the manufacture of steel.

(ii) In the extraction of metals (as a reducing agent).

Q8. Explain the process of the formation of petroleum.

Ans. Petroleum was formed from dead organisms that got buried in the sea millions of years ago. These dead bodies got covered with layers of sand and clay. Lack of air, high temperature, and high pressure transformed these dead organisms into petroleum and natural gas.

Q9.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.

S. No.	Year	Shortage (%)
1 2 3 4 5 6 7	1991 1992 1993 1994 1995 1996 1997	7.9 7.8 8.3 7.4 7.1 9.2 11.5

 Ans.

Q10. What are exhaustible natural resources?

Ans.

Exhaustible Natural Resources are limited natural resources. They can be exhausted by human activities and cannot last for a long time if used unnecessarily. Examples, Forests, Wildlife, Minerals, Coal, Petroleum, Natural Gas, etc.

Q11. What are inexhaustible natural resources?

Ans.

Inexhaustible Natural Resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities. Examples, Sunlight, air, etc.

Q12. Why natural gas is called a clean fuel?

Ans.

Natural gas is called a clean fuel because it is less polluting fuel. It can easily be transported through pipes. It is used as a fuel for transport vehicles and for burning in homes and factories.

Q13. What are the uses of coal?

Ans.

Coal is a black hard substance. It was used in railway engines to produce steam. Now it is used to cook food. It is used in thermal power plants to produce electricity. It is used as a fuel in industries.

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