Chapter 2: Coal and Petroleum | Science Class 8th - JK NCERT Solutions

Chapter 2: Coal and Petroleum | Science Class 8th

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

Ans: The following are the benefits of using compressed natural gas (CNG) and liquefied petroleum gas (LPG) as fuels:

(i)They can be directly burned.

(ii) They can be easily transported via pipelines.

(iii) They are clean fuels that emit no smoke when burned.

(iv) When burned, they produce a lot of heat energy.

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

Ans: Bitumen, a petroleum product, is used in road surfacing.

Q3. Describe how coal is formed from dead vegetation. What is this process called?

Ans: Natural events like earthquakes, floods, and storms caused lush forests to get submerged under the soil millions of years ago. As more and more soil was dumped on top of them, these were squeezed. They were exposed to extremely high pressure and temperature when they were buried deeply in the ground. These slowly turned into coal in these circumstances. Carbonization is the term used to describe the process of creating coal from dead plants.

Q4. Fill in the banks.

(a) Fossil fuels are ________, ________ and _________.

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

Ans:

(a) Fossil fuels are Coal, Petroleum and Natural Gas.

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

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: It takes millions of years for fossil fuels to develop from dead plants and animals that are buried deep inside the Earth. They cannot form in a laboratory because they need extremely high temperatures and pressures. Fossils are scarce as a result. As a result, if fossil fuels are used at this rate, they will eventually run out.

Q7. Describe the characteristics and uses of coke.

Ans: Coke has the following characteristics:

it is tough
it is porous
it is black in colour

Uses of coke:

(i) In the manufacture of steel.

(ii) During metal extraction (as a reducing agent).

Q8. Explain the process of the formation of petroleum.

Ans: Petroleum was formed millions of years ago when dead organisms were buried in the sea. These dead bodies were covered with sand and clay layers. Due to a lack of oxygen, high temperatures, and high pressure, these dead organisms were converted 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: Natural resources that are inexhaustible are scarce. They can be depleted by human activities and will not last long if used excessively. Forests, wildlife, minerals, coal, petroleum, natural gas, and so on are examples.

Q11. What are inexhaustible natural resources?

Ans: Natural resources that are inexhaustible are abundant in nature and are unlikely to be depleted by human activity. Sunlight, for example, or air.

Q12. Why natural gas is called a clean fuel?

Ans: Natural gas is referred to as a clean fuel because it emits less pollution. It is easily transportable via pipes. It is used as a fuel in vehicles as well as in homes and factories.

Q13. What are the uses of coal?

Ans: Coal is a black, brittle substance. It was used to generate steam in railway engines. It is now used to cook food. It is used to generate electricity in thermal power plants. In industries, it is used as a fuel.