NCERT Class 8 Science Chapter 3 ‘Coal and Petroleum’: Notes and Solutions (Free PDF)

Well-written and organised notes play a key aspect in the learning process. When it comes to revision, then also notes are our saviour. Seeing the importance of the same, in this bog on NCERT Solutions and Notes Class 8 Science Chapter 3: Coal and Petroleum,  we have provided summarised notes of the chapter. These will help you ace your exams and can also be used for quick revision. Let’s explore this blog. 

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Explore all the Chapters of Class 8 Science:

Chapter 1	Chapter 2	Chapter 3
Chapter 4	Chapter 5	Chapter 6
Chapter 7	Chapter 8	Chapter 9
Chapter 10	Chapter 11	Chapter 12
Chapter 13

Class 8 Science Chapter 3 Coal and Petroleum Notes

Let’s explore the summarised notes of all of Class 8 Science Chapter 3 Coal and Petroleum. Herein, are the notes where our experts have tried and explained all the major topics in short and simple sentences for you to understand easily.

Types of Resources

Resources that are obtained from nature are known as natural resources. This includes air, wood, water, soil, etc. Now, based on the availability of these resources in nature, natural resources are classified into two types:-

1. Inexhaustible Natural Resources:- These resources are present in unlimited quantities and are unlikely to get exhausted by human activities. Example:- sunlight, air, etc. 
2. Exhaustible Natural Resources:- These resources are present in limited amounts and can be exhausted by human activities. Examples:- forests, wildlife, minerals, coal, petroleum, natural gas etc.

Coal and Petroleum are formed from the dead remains of living organisms which are known as fossils, hence, they are known as Fossil Fuels.

Also Read:- Types of Water Pollution

Class 8 Science Chapter 3 Coal and Petroleum Notes: Coal

Coal is one of the fossil fuels and is hard a stone and is dark in colour. It comes under the category of exhaustible natural resources. It is used as fuel in various industries such as thermal power plants, earlier it was used in steam engines and even to cook food.

Formation of Coal and its Types

Here is how coal is formed: 

• About 300 million years ago the earth had dense forests in low-lying wetland areas.
• These forests got buried under the soil due to natural processes, like flooding.
• More soil got deposited over them and they got buried deep under it. 
• As they continued to sink, they got more compressed and the temperature started to rise.
• Now, under the effect of this high temperature and pressure, they slowly got converted to coal.

This process of conversion of dead vegetation into coal, which is mainly carbon, is known as carbonisation. Now, some products are produced by processing coal such as coke, coal-tar, coal gas, etc. Let’s have a look at them.

Also Read:- What is a Natural Disaster?

Types of Coal

Now, let us learn about different types of coal:

1. Coke

• It is a porous, tough, and black substance.
• It is almost a pure form of carbon.
• Coke is used in the manufacture of steel and the extraction of many metals.

2. Coal Tar

• It is a thick black liquid that is a mixture of 200 substances and has an unpleasant smell.
• Naphthalene balls are obtained from coal tar.
• The products of coal tar are used in the manufacturing of several daily-use as well as industry products such as dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc

3. Coal Gas

• It is obtained during the processing of coal to get coke.
• It is used as a fuel in many industries that are situated near the coal processing plant.

Class 8 Science Chapter 3 Coal and Petroleum Notes: Petroleum

Petroleum is derived from the word “petra” meaning “rock” and “oleum” meaning “oil”. It is one of the fossil fuels and is obtained by mining between the rocks from under the Earth. Petrol and diesel are obtained from it. Petrol is used to run light motor vehicles such as motorcycles, scooters, and cars and diesel is used to run heavy motor vehicles such as trucks, tractors, etc. 

Formation of Petroleum

Let us look at how petroleum was formed:

• It was formed from sea organisms.
• When the sea organisms died, they settled at the bottom of the sea. 
• Over time they got covered with layers of sand and clay. 
• Due to the high pressure, absence of air and high temperature, they slowly got converted into petroleum and natural gas. 

Refining of Petroleum

Petroleum is a dark-coloured liquid with an unpleasant smell that is a mixture of many substances such as petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc.

The process of separation of various constituents/fractions of petroleum is known as petroleum refining and is carried out in a petroleum refinery. 

Constituents of petroleum along with their uses

In the table below, there are mentioned different constituents of petroleum along with their respective uses:

S.No.	Constituents of Petroleum	Uses
1	Petroleum Gas in Liquid form(LPG)	Fuel for home and industry
2	Petrol	Motor fuel, aviation fuel, solvent for dry cleaning
3	Kerosene	Fuel for stoves, lamps and for jet aircraft
4	Diesel	Fuel for heavy motor vehicles, electric generators
5	Lubricating oil	Lubrication
6	Paraffin wax	Ointments, candles, vaseline etc
7	Bitumen	Paints, road surfacing

Natural Gas

Here are the key features of natural gas:

• It is an important fossil fuel.
• Its transport is easy and done via pipes.
• It is stored under high pressure as compressed natural gas (CNG).
• There are many uses of natural gas ranging from being used as fuel for power generation to being used as a fuel for light motor vehicles.
• It is a much cleaner fuel.
• Natural gas is also used as a starting material for the manufacture of a number of chemicals and fertilisers.
• In our country, natural gas has been found in Tripura, Rajasthan, Maharashtra and in the Krishna Godavari delta.

Limitations of Fossil Fuels

Here are some limitations of fossil fuels:

• Some natural resources are exhaustible like fossil fuels, forests, minerals etc.
• The known reserves of fossil fuels will last only a few hundred years.
• Their use is also linked to global warming.
• It is therefore necessary that we use these fuels only when necessary. This will result in a better environment, a smaller risk of global warming and their availability for a longer period.

In India, the Petroleum Conservation Research Association (PCRA) advises people on how to save petrol/diesel while driving. Their tips are mentioned below:-

• Drive at a constant and moderate speed as far as possible.
• Switch off the engine at traffic lights or at a place where you have to wait.
• Ensure correct tyre pressure.
• Ensure regular maintenance of the vehicle.

Also Read:- Essay on Global Warming

Important Definitions in NCERT Class 8 Science Chapter 3 Coal and Petroleum

Here are the important definitions in Class 8 Science Chapter 3 Coal and Petroleum.

• Natural Resources: Resources that are obtained from nature are known as natural resources.
• Inexhaustible Natural Resources: These resources are present in unlimited quantities and are unlikely to get exhausted by human activities. Example:- sunlight, air, etc. 
• Exhaustible Natural Resources: These resources are present in limited amounts and can be exhausted by human activities. Examples:- forests, wildlife, minerals, coal, petroleum, natural gas etc.
• Fossil Fuels: Coal and Petroleum are formed from the dead remains of living organisms which are known as fossils, hence, they are known as fossil fuels.
• Petroleum Refining: The process of separation of various constituents/fractions of petroleum is known as petroleum refining and is carried out in a petroleum refinery. 

Explore NCERT Solutions of all Chapters of Class 8 Science:

Chapter 1	Chapter 2	Chapter 3
Chapter 4	Chapter 5	Chapter 6
Chapter 7	Chapter 8	Chapter 9
Chapter 10	Chapter 11	Chapter 12
Chapter 13

Download the NCERT Class 8 Science Chapter 3 Solutions PDF Here!

NCERT Solutions of Class 8 Science Chapter 3 Coal and Petroleum

Let us now explore NCERT Solutions of Class 8 Science Chapter 3 to get answers to all writing questions in the lesson Coal and Petroleum.

Exercise Questions

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

Soln:

The advantages of using CNG and LPG as fuels are as follows:

• CNG and LPG are much cleaner fuels and they cause less pollution and do not release smoke when burnt.
• CNG and LPG both burn easily.
• CNG and LPG can be transported easily through pipelines as compressed and liquified gases.
• CNG and LPG give a lot of heat energy when burnt and can be directly used for burning at home or in industries.

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

Soln:

Bitumen is used for the surfacing of roads.

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

Soln:

About 300 million years ago the earth had dense forests in low-lying wetland areas. These forests got buried under the soil due to natural processes, like flooding. More soil got deposited over them and they got buried deep under it. As they continued to sink, they got more compressed and the temperature started to rise. Now, under the effect of this high temperature and pressure, this dead vegetation slowly got converted to coal.

This process of conversion of dead vegetation into coal, which is mainly carbon, is known as carbonisation. 

 4. Fill in the blanks.

(a) Fossil fuels are  ____________,  ____________, and ____________ .

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

(c) The least polluting fuel for a vehicle is ______________ .

Soln:

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

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

(c) The least polluting fuel for a vehicle is Compressed Natural Gas (CNG).

5. Tick True/False against the following statements.

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

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

(c) Coke is the most 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)

Soln:

a) False

b) False

c) True

d) True

e) False

6. Explain why fossil fuels are exhaustible natural resources.

Soln:

The fossil fuels are formed when dead vegetation gets covered with many layers of soil. These get compressed and under high temperatures and pressure, they slowly get converted to fossil fuels. This cannot be carried out artificially as this process takes over millions of years. These fossil fuels are present in limited amounts and will last only a few hundred years making them exhaustible natural resources. It is therefore necessary that we use these fuels only when necessary. This will result in a better environment, a smaller risk of global warming and their availability for a longer period.

7. Describe the characteristics and uses of coke.

Soln:

Characteristics:

i) Coke is tough.

ii) Coke is porous.

iii) Coke is black.

Uses:

i) In the manufacturing of steel.

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

8. Explain the process of the formation of petroleum.

Soln:

It was formed from the sea organisms. When the sea organisms died, they settled at the bottom of the sea. Over time they got covered with layers of sand and clay. Due to the high pressure, absence of air and high temperature, they slowly got converted into petroleum and natural gas. 

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