Energy
The transfer of energy between bodies can take the form of heat or work, both of which can be derived from natural resources.
Coal
Under the high temperature and pressure inside the earth, buried plants are converted into coal. Coal is black and hard. Coal is used in households, industry, heat engines, railways, etc.
When we heat coal in the air, carbon dioxide is produced. When coal is processed in industry, the following products are produced.
- Coke - It is the pure form of carbon. It is a porous, black and formidable substance. It is used in the extraction of various metals.
- Coal tar - A thick, black liquid with an unpleasant odour is coal tar. Coal tar is used to make various products used to manufacture plastics, paints, perfumes, synthetic dyes, medicines, explosives, etc.
- Coal gas - This gas is obtained when coal is converted into coke. Coal gas is used in many industries.
Petroleum
Petroleum is a ruinous oily liquid with a pungent odour. It consists of various components such as petrol, diesel, lubricating oil, paraffin, etc.
- Petroleum gas is used in liquid form in households and industry.
- Petrol is used as fuel in automobiles.
- Paraffin is used as fuel in households.
- Diesel is used as fuel in vehicles and generators.
- Paraffin wax is used to make candles, wax and ointments.
- Bitumen is used for road construction.
Coal and Petroleum Sample Questions for Class 8
Question 1
Which of the following is regarded as the best variety of coal?
A. Lignite
B. Anthracite
C. Peat
D. Bituminous
Question 2
Match both the columns and select the correct option from the codes given below.
A. A.-(I);
B. -(III);
C. -(IV);
D. -(II)B. A.-(II); B.-(I); C.-(III); D.-(IV)C. A.-(IV); B.-(I); C.-(II); D.-(III)D. A.-(IV); B.-(I); C.-(III); D.-(II)
Question 3
The residue left behind after the dry distillation of coal :
A. coal tar
B. coal gas
C. coke
D. ammonical liquor
Question 4
Reckitt and Coleman are makers of the Cherry Shoe polish. Why do black shoe polishes have an oily feel?
A. Shoe polishes is a mixture of oil and powdered graphite
B. On exposure to air, these undergo chemical changes and produce oily substance
C. Vapour of some amount of oil is left over, after its preparation
D. These are formed by dissolving charcoal in oil
Question 5
The main constituents of petroleum gas is:
A. butane
B. propane
C. methane
D. ethane