CBSE Class 8 Science Revision Notes Chapter 5

Class 8 Science Chapter 5 Notes

CBSE Class 8 Science Revision Notes Chapter 5 – Coal and Petroleum

Students can rely on Coal and Petroleum Chapter 5 Class 8 revision notes to assist them in learning all chapter topics. Extramarks Revision Notes are accurate and written in simple language by subject matter experts. These notes are useful for a quick review of the topics covered in a chapter. Extramarks notes will be a student’s last-minute revision guide providing all the necessary information in a nutshell, to revise the entire syllabus quickly and easily.

Revision Notes for CBSE Class 8 Science Chapter 5

Access Class VIII Science Chapter 5 – Coal and Petroleum Notes

Extramarks notes will be a student’s last-minute revision guide providing all the necessary information in a nutshell, to revise the entire syllabus quickly and easily.

Here are some of the key concepts  mentioned in the chapter: 

Fossil Fuels:

  • Nonrenewable natural resources include coal, petroleum, and natural gas.
  • Fossil fuels were created millions of years ago from the dead remains of living species.
  • They are depletable and cannot be replenished.


  • Coal is a black substance with the same hardness as stone.
  • Coal is one of the fuels used in food preparation.
  • It was once used to generate steam to power railway engines.
  • It is also used in thermal power plants to generate electricity.
  • In numerous and differing industries, coal is also employed as an energy source.
  • Under intense pressure and high temperatures, dead plants are gradually transformed into coal.
  • Because coal is primarily composed of carbon, carbonisation is the lengthy process of converting dead plants into coal.
  • Coal is classified as a fossil fuel because it is made from plant waste.
  • Carbon dioxide gas is the main byproduct of burning coal in the presence of oxygen.
  • Coal is processed in the industry to make useful products such as coke, coal tar, and coal gas.


  • Coke is a dark, rough, porous liquid.
  • It is a carbon that is almost completely free of impurities.
  • Coke is used in the manufacture of steel as well as the extraction of various metals.

Coal Tar:

  • Coal tar is a dark, thick liquid with an unpleasant odour.
  • It is composed of nearly 200 different chemicals.
  • Many common and industrial products, such as synthetic colours, medicines, explosives, fragrances, plastics, paints, photographic materials, roofing materials, and others, are made from coal tar as a starting ingredient.
  • Naphthalene balls, which are used to ward off insects like moths, are also made using coal tar.
  • In place of coal tar, bitumen, a petroleum product, is now used to metalise roads.

Coal Gas:

  • Coal gas is created during the coke-making process.
  • Coal processing plants are a common source of energy for many nearby industries.
  • Coal gas was used for street lighting.
  • Currently, it serves as a heat source rather than a light source.


  • Petrol and diesel are derived from petroleum, which is a natural resource.
  • Petroleum is derived from the words Petra (rock) and oleum (oil), as it is extracted from the earth’s crust.
  • Petroleum is composed of organisms that live in water.
  • When these organisms died, their remains sank to the seafloor and were covered by layers of sand and clay. .
  • Over millions of years, the lack of air, high temperature, and high pressure converted the dead organisms into petroleum and natural gas.

Refining of Petroleum:

  • Petroleum is a dark-coloured, thick, viscous liquid.
  • It has an offensive odour.
  • It is made from lubricating oil, paraffin wax, petroleum gas, gasoline, and other materials.
  • The process of separating the various constituents/fractions of petroleum is known as refining.
  • It is set in a petroleum refinery.
  • Many valuable chemicals are produced using petroleum and natural gas. These also go by the term petrochemicals.
  • They are used in the production of detergents, fibres (polyester, nylon, acrylic, and so on), polyethene, and other man-made polymers.
  • Fertilisers are made from natural gas derived from hydrogen gas (urea).
  • Because of its high commercial value, petroleum is sometimes referred to as “black gold.”

Natural Gas:

  • Compressed natural gas is a crucial fuel because it can be compressed and stored at high pressure and is easy to transfer through pipes.
  • It has a high calorific value and does not pollute the environment.
  • Electricity is generated using CNG.
  • It is now used as fuel for the transportation of vehicles.
  • It is a more environmentally friendly fuel.
  • The production of numerous chemicals and fertilisers also uses natural gas as a raw material.
  • India possesses massive natural gas reserves.
  • In India, natural gas has been discovered in Tripura, Rajasthan, Maharashtra, and the Krishna-Godavari delta.
  • The supply of coal and petroleum is limited. They should be used with caution.
  • The Petroleum Conservation Research Association (PCRA) in India provides driving tips on how to save petrol and diesel.
  • Their recommendations are as follows:
  1. Drive as far as possible at a consistent and moderate speed.
  2. Turn off the engine at traffic lights or other locations where the vehicle is stationary;
  3. Maintain adequate tyre pressure.
  4. Make sure the car is serviced on a regular basis.

Coal and Petroleum Class 8 Science Revision Notes Chapter 5

The revision notes offered by Extramarks are intended to help students to memorise and understand the essential topics of Chapter 5 of Class 8 Coal and Petroleum. Each topic is explained briefly and in an easy-to-understand language by subject matter experts.

Students can plan ahead and create a stress-free learning experience with these notes. They can effectively revise the entire chapter with the concise key concepts given in these notes, which will help them feel more confident before exams. Extramarks Revision Notes are available on the website, which students can access anytime at their convenience.

A Glimpse into Chapter 5 Coal and Petroleum

Introduction to Coal

Coal is a dark-coloured fossil fuel. It is extracted from the earth and used for a variety of purposes.

Uses of Coal

There are numerous uses for coal, including:

  • Face packs and cosmetics contain activated charcoal.
  • Thermal coal is used to generate electricity.
  • Steel is manufactured using coke, iron ore and limestone.

Coal and Coke

What is Coal?

Coal is a dark sedimentary rock formed in coal fields and mines. Coal is extracted from these coal beds and mines. Coal is formed by a natural process that takes millions of years.

What is Coke?

In addition to having a high carbon content, coal also has a small amount of coke-like impurities. Coke is often a grey, brittle, and hard substance found in nature and is made up of components that come from the destructive distillation of low-ash, low-sulphur bituminous coal that is derived from carbonaceous material. It is also known as pet coke and petroleum coke.

Uses of Coke

  • Due to its relatively smoke-free production, it can be utilised as a clean fuel in dwellings.
  • The process of creating gas from water also uses coke.
  • When smelting iron ore, it serves as a reduction agent.
  • Blacksmiths also use it as fuel.

Coal Gas and Coal Tar

What is Coal gas?

Coal gas is a byproduct of destructive coal distillation that consists of hydrogen, methane, carbon monoxide, and volatile hydrocarbons. It is a flammable gas produced from coal delivered via a piped system.

Uses of Coal Gas

  • Lighting is powered by coal gas.
  • It is a type of fuel.
  • Coal gas is also used as a source of light.

What is Coal Tar?

In the process of producing coke and gasifying coal, a thick, black liquid known as coal tar is created. There are several different organic substances present, including benzene, naphthalene, phenols, and aniline. Coal tar is used for medical and industrial purposes.

Uses of Coal Tar

  • Coal tar is used to cover and beautify the underlying pavement.
  • Coal is also used to make parking lot seal-coat items.
  • Coal tar is used to make roads.
  • Coal tar is flammable in nature. As a result, it is used for heating.

Natural Gas

What is Natural Gas?

Natural gas is a fossil fuel that can be burned. It occurs naturally and is composed of approximately 95% hydrocarbon methane, with the remaining 5% composed of nitrogen, carbon dioxide, helium, or hydrogen sulphide. It takes millions of years to form.


  • It is utilised in automobiles as compressed natural gas (CNG) (Compressed Natural Gas).
  • In the rubber and plastic industries, it serves as a chemical feedstock.
  • Glass, paint, and clothing are some products made from natural gas.

What is Petroleum?

Petroleum is a naturally occurring material. It is a dark liquid that is present beneath the earth’s surface. Numerous goods, such as lubricating oil, diesel, and gasoline, are produced using petroleum. Fractional distillation can be used to isolate its constituents.

Formation of Petroleum

Petroleum takes millions of years to form. Millions of animals, like plant-based matter, have lived and died over time to become fossilised.

Because of the presence of bacteria, the decomposed organic matter has been buried deeper and deeper over time. The carcasses of dead animals are subjected to extreme pressure, heat, and lack of oxygen. Over a million years, these conditions convert the dead material into petroleum and coal.

Crude oil and petroleum both refer to liquefied forms of decomposed organic matter. Crude oil is taken out of the ground using deep wells. Various petroleum products are made from this crude oil after it has been refined and processed—for example, kerosene, diesel fuel, lubricants, and many others.

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Fun Facts About the Products Produced in the Petroleum Refining Process

During the refinement of petroleum, did you realise that we produce more than just petroleum gas? The refinement of petroleum also yields kerosene and gasoline, which are domestic fuel options.