Coal and Petroleum Class 8 Notes | Chapter 5

Coal and Petroleum|Class 8

Coal and Petroleum

Natural Resources:

Natural resources are obtained from nature and can be categorized as inexhaustible (present in unlimited quantity) and exhaustible (present in limited quantity).

Inexhaustible Natural Resources:

Inexhaustible natural resources are present in unlimited quantities in nature.

Examples of inexhaustible natural resources include sunlight, air, and water.

These resources are also known as renewable resources as they can be replenished naturally and are not likely to be exhausted by human activities.

Exhaustible Natural Resources:

Exhaustible natural resources have a limited amount available in nature.

Examples of exhaustible natural resources include forests, wildlife, minerals, coal, petroleum, and natural gas.

Human activities can deplete these resources, and if not managed carefully, they can be exhausted over time.

Fossil Fuels:

Fossil fuels are exhaustible natural resources formed from the remains of dead plants and animals. Coal, petroleum, and natural gas are examples of fossil fuels.


Coal is a black, non-crystalline fossil fuel formed from the remains of vegetation that existed millions of years ago. It is used as a fuel in various industries.

Formation of Coal:

Coal is formed from dead vegetation through the process of carbonization, which occurs under high temperature and pressure over a long period.

Types of Coal:

There are four types of coal: anthracite, bituminous, sub-bituminous, and lignite. They differ in carbon content and energy value.

Destructive Distillation of Coal: Destructive distillation is the process of heating coal in the absence of air. It produces by-products like coke, coal tar, ammonia liquor, and coal gas.


Petroleum is a dark, oily liquid obtained from the decomposition of dead marine organisms over millions of years. It is a mixture of hydrocarbons and is used as a fuel and for various industrial purposes.

Fractional Distillation of Petroleum:

Fractional distillation is the process used to separate different components of petroleum based on their boiling points. This process yields products like petrol, diesel, kerosene, lubricating oil, paraffin wax, and bitumen.

Natural Gas:

Natural gas is a fossil fuel consisting mainly of methane. It is a clean-burning fuel and is used for heating, cooking, and electricity generation.

Conservation of Fossil Fuels:

Fossil fuels are limited resources and need to be conserved. We can conserve them by using energy-efficient appliances, practicing fuel economy in vehicles, and promoting renewable energy sources.

Here is a table chart showing the various constituents of petroleum and their uses:

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

The constituents of petroleum and their uses are as follows:

  1. Petroleum Gas in Liquid form (LPG): Used as fuel for home and industry.
  2. Petrol: Used as motor fuel, aviation fuel, and solvent for dry cleaning.
  3. Kerosene: Used as fuel for stoves, lamps, and jet aircrafts.
  4. Diesel: Used as fuel for heavy motor vehicles and electric generators.
  5. Lubricating oil: Used for lubrication in machines and engines.
  6. Paraffin wax: Used to make ointments, candles, vaseline, and grease.
  7. Bitumen: Used for road surfacing, making black paints, and waterproofing roofs.

Read More: Microorganisms: Friend and Foe | Class 8 Notes | Science Chapter 2


The petroleum product used for surfacing roads is "bitumen".

Coal is formed from dead vegetation through a process called "coalification" or "carbonization."

300 million years ago, dense forests grew in wetland areas. Over time, floods buried these forests under soil. The buried plants were compressed as more soil accumulated. With increasing temperature and pressure, the plants underwent carbonisation, transforming into coal. Coal is mainly composed of carbon and is classified as a fossil fuel, originating from ancient vegetation.

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

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

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

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

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

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

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

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

Fossil fuels are exhaustible natural resources because their formation take millions of years to form from dead vegetation and animals that get buried deep inside the earth. They require high heat and pressure for their formation which cannot be provided in the laboratories. Therefore, once these resources are extracted and used, they cannot be easily replenished within a human timescale.

Coke is a solid carbonaceous material derived from coal through the process of destructive distillation. It has the following characteristics and uses:

  • Characteristics: Coke is almost pure carbon and has high carbon content. It is strong, porous, and resistant to high temperatures.
  • Uses: Coke is primarily used as a fuel and reducing agent in the production of iron and steel. It provides the necessary heat and carbon for the smelting process. Coke is also used in the production of electrodes for electric arc furnaces and as a fuel in some industrial processes.

Over millions of years, the absence of air, high temperature, and pressure transformed these organic remains into petroleum and natural gas. The layer containing petroleum and gas is positioned above the water layer because oil and gas are lighter than water and do not mix with it.

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