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
Coal is formed by the process of:
A. carbonisation
B. distillation
C. vapourisation
D. evaporation
Question 2
____ is the common variety of coal used in household.
A. Anthracite
B. Bituminous
C. Peat
D. Lignite
Question 3
____ has the lowest percentage of carbon.
A. Lignite
B. Bituminous
C. Anthracite
D. Peat
Question 4
Fuels burn to produce heat, light and ______
A. CO2 + water vapour
B. CO + O2
C. CO2 + H2
D. CO + H2
Question 5
Fuels combine with _____ to produce heat and light.
A. CO2
B. CO
C. O2
D. H2