NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum

Chapter 5 explains the chief energy resources like coal and petroleum. Students will learn the classification and formation of coal and petroleum, by-products of coal and oil, natural gas, etc.

Students will learn about the difference in natural resources and man-made resources. Under natural resources, they will learn about exhaustible resources like forests, coal, etc. and inexhaustible resources like air and sunlight.

The chapter of NCERT solutions for class 8 science will explain how coal is formed and why coal, petroleum and natural gas are known as fossil fuels.

👉 Download Chapter 5 Coal and Petroleum PDF

Question 1: What are the advantages of using CNG and LPG as fuels?

Solution: Generally, fuels when burnt releases various harmful gases into the atmosphere apart from the production of heat. CNG and LPG when used as fuels have the following benefits:

They produce a lot of heat energy.

They do not pollute the environment as other fuels do. They are clean fuels.

They can be compressed easily and transported to various locations.

They can be stored easily in cylinders.

Question 2: Name the petroleum product used for surfacing of roads.

Solution: Petroleum refining gives various products like petroleum gas, kerosene, lubricating oil, diesel, petrol, bitumen and naphtha. Out of them, bitumen is used for surfacing of roads.

Question 3: Describe how coal is formed from dead vegetation. What is this process called?

Solution: Coal formation takes millions of years. It is formed from dead plants that lived millions of years ago and got buried deep inside the layers of earth. With the passage of time, water and soil accumulates on top of their layers. This creates high pressure and temperature inside and pushes oxygen out. This process of conversion of dead plants into carbon (coal) due to physical and chemical changes deep inside the earth is called carbonisation.

Question 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 vehicle is ______________.

Solution:

Fossil fuels are coal, petroleum and natural gas.

Fossil fuels are fuels that are formed from dead plants and animals and took million years for their formation. Examples are coal, petroleum, and natural gas.

Process of separation of different constituents from petroleum is called petroleum refining.

Petroleum itself is not used directly. It is processed to give different useful compounds like petrol, diesel, naphtha, bitumen, and petroleum gas. This process of separation of petroleum into different constituents by fractional distillation method is called petroleum refining.

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

Fuels generally produce heat and harmful gases on burning. Natural gas when compressed is called compressed natural gas. It produces least harmful gases and is safe to use.

Want to download NCERT solutions for class 8 maths Comparing Quantities? Get access to free PDF below:

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Question 5. 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 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)

Solution:

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

Fossil fuels cannot be made the laboratory. These are formed by natural changes that occur inside the earth on dead plants and animals.

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

CNG release less harmful gases when burnt as compared to petrol. Due to this it is called clean fuel.

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

On heating coal, it gives coal tar, coal gas, coke, and ammonical liquor. Out of them, coke contains maximum amount of carbon.

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

Coal tar is a mixture of 200 carbon compounds.

(e) Kerosene is not a fossil fuel. -False

Kerosene is obtained by petroleum refining. It cannot be prepared in laboratories. So, it is a fossil fuel.

Question 6. Explain why fossil fuels are exhaustible natural resources.

Solution: Fossil fuels are formed from dead plants and animals that got buried in the earth millions of years ago. Their formation takes a long time. They cannot be artificially synthesized in the laboratories. So, they are limited and can exhaust if used at a rapid rate. Therefore, fossil fuels are exhaustible natural resources.

Question 7. Describe characteristics and uses of coke.

Solution:

Characteristics of coke: It is a black-coloured solid substance It is hard and porous. It contains maximum carbon content.

Uses of coke: It is used as a reducing agent in the extraction of various metals. It is also used during steel manufacturing.

Question 8. Explain the process of formation of petroleum.

Solution: Petroleum was formed from dead animals that lived millions of years ago and got buried deep inside the sea with water, sand, and other rock particles. Due to high temperature and pressure and lack of air inside the layers of earth, this dead remains underwent many physical and chemical changes and then converted into black and thick liquid called petroleum and natural gas.

Question 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 the X-axis.

Links to Other Resources for Class 8 Science

Other Class 8 Science Related Links
Understanding Structure and Functions of a Cell
Deforestation, Afforestation and Reforestation
Frictional Force Definition, and Types with Example
Compare LPG and Wood as Fuel
Water Pollution Causes and Effects with Example