Coal and Petroleum Class 8 Notes - Chapter 5

Various materials that we use for our basic needs are either found in nature or are made by human efforts. Based on the availability of resources in nature, natural resources are broadly classified into two kinds as:

  • Inexhaustible Natural Resources – Resources that are inexhaustible and unlikely to get exhausted by human activities. Examples: Air, Sunlight
  • Exhaustible Natural Resources – Resources that are limited and are exhausted by human activities. Example: Forest, wildlife, mineral, petroleum, coal, etc.

In class 8 science chapter 5, we discuss exhaustible natural resources like coal, natural gas and petroleum. These resources are the resultant of the decomposition of dead remains of buried living organisms. Hence they are known as fossil fuels.

Formation Of Coal And Petroleum

Around 300 million years ago, the dense forest in wetland areas was buried under the soil due to flooding. They were compressed, as more and more soil deposited over them. Under high pressure and temperature, the dead plants were converted to coal.

The other exhaustible natural resource petroleum was formed from the organisms living under the sea. As the organisms living under the sea died and settled at the bottom of the sea, they were covered with layers of clay and sand. These dead organisms with layers of sand and clay transformed into petroleum and natural gas under high pressure and temperature.

Refining of Petroleum

Petroleum needs to be refined in order to transform it into useful products that will benefit the customers and industries. The separation of various constituents of petroleum is known as refining and is carried out in a petroleum refinery. Petroleum is a dark oily liquid composed of constituents such as diesel, petrol paraffin wax and lubricating wax. The various constituents of petroleum and their uses are given below in a table

Constituents of Petroleum Uses
Petrol Motor Fuel, Aviation Fuel
Diesel Fuel for electric generators and heavy motor vehicles
Petroleum Gas in Liquid form (LPG) Home and industry fuel
Kerosene Fuels for lamps, stoves and jet aircrafts

As coal and petroleum resources are limited and exhaustible, we should use them judiciously.

Coal And Petroleum Class 8 Extra Questions

  1. Explain the process of formation of petroleum
  2. Explain how coal is formed from dead vegetation.
  3. What is the process of separation of different constituents from the petroleum called?
  4. Why are fossils fuels an exhaustible natural resource?

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