NCERT Class 8 Science Chapter 5 Coal and Petroleum | Important Questions

Here are important questions from NCERT Class 8 Science Chapter 5 Coal And Petroleum. Multiple Choice Questions from this chapter can be found here.

1. What are natural resources?

These are materials obtained from nature. Examples: land, air, water

2. What are the two kinds of natural resources?

Exhaustible resources and inexhaustible resources

3. What are inexhaustible natural resources?

These are materials present in nature in unlimited quantity. These resources are unlikely to be exhausted by human activities. Examples are: sunlight and air

4. What are exhaustible natural resources?

These are natural resources that are available only in a limited quantity. Excessive consumption of these resources will exhaust them. Examples are: forest, coal, petroleum, wildlife etc.

5. How were coal and petroleum formed?

They were formed from the dead remains of living organisms (fossils).

6. Why are coal and petroleum called fossil fuels?

Coal and petroleum were formed from the dead remains or fossils of living organisms. Hence, they are called fossil fuels.

7. What are some uses of coal?

Coal is one of the fuels used for cooking food. Earlier, coal was used in railway engines to produce the steam that would run the train. Coal is also used in thermal power plants to produce electricity. In addition, there are many other industries that use coal as a fuel.

8. How were coal deposits formed?

Around 300 million years ago, there were dense forests in many low lying areas. Due to natural disasters like flooding, many of these forests got submerged in water and was later buried under the soil. Over the years more and more soil got deposited over them and they were compressed. As they sank deeper and deeper, the temperature also rose. Under high pressure and temperature, these dead plants got converted to coal.

9. What is carbonization?

Coal mainly contains carbon. The slow process of conversion of dead plants into carbon rich coal is called carbonization.

10. Name some products obtained from coal?

Coke, coal tar and coal gas

11. What is coke?

Coke is a product obtained by processing coal. It is a tough, porous and black substance. It is an almost pure form of carbon and is used in the manufacture of steel and in the extraction of several metals.

12. What is coal tar?

It is a product obtained by processing coal. It is a black and thick liquid. Coal tar is a mixture of nearly 200 substances. Products obtained from coal tar are used for manufacturing substances like synthetic dyes, drugs, plastics, explosives, paints, roofing materials etc.

13. What is coal gas?

Coal gas is a product obtained during the processing of coal to get coke. It is a fuel for many industries.

14. How was petroleum formed?

Petroleum was formed from sea organisms. As they died, their bodies got deposited at the bottom of the sea. Over years, they got covered by sand and clay. These dead organisms were transformed into petroleum and natural gas over millions of years due to absence of air, high temperature and high pressure.

15. Name the main constituents of petroleum

The main constituents of petroleum are petrol, diesel, lubricating oil, paraffin wax etc.

16. What is refining?

Refining is the process of separating various constituents of petroleum. It is carried out in a petroleum refinery.

17. What are petrochemicals?

These are useful substances obtained from petrol and natural gas.

18. Name some uses of petrochemicals?

Petrochemicals are used in the manufacture of detergents, fibres, polythene and other plastics. Hydrogen obtained from natural gas is used for manufacturing the fertiliser urea.

19. Why is natural gas an important fossil fuel?

Natural gas is an important fuel because it has various uses. It is less polluting than petrol or diesel and hence it is now widely used as a fuel for transport vehicles. It can be transported easily through pipes. It is stored under high pressure as compressed natural gas (CNG). One of the biggest advantages of CNG is that it can be used directly for burning in homes and factories. Natural gas is also used as a starting material for the manufacture of various chemicals and fertilisers.

20. Why should we limit the use of coal and petroleum?

Coal and petroleum are exhaustible natural resources. That means their supply is limited. It took dead organisms millions of years to get converted into fossil fuels. The available reserves of these fuels will last only a few hundred years and hence we have to limit our consumption of fossil fuels. Also, the burning of fossil fuels is one of the biggest causes of air pollution. They also contribute to global warming. By simply limiting our consumption of these fossils we can conserve them for longer periods and also improve our air quality.

21. List some ways to save petrol or diesel while driving

• Drive at a constant and moderate speed.
• At traffic lights or at other places where you have to halt, switch off the engine.
• Make sure that tyre pressure is correct.
• Ensure regular maintenance of the vehicle.