Burning of which of the following fuels produces the least amount of carbon dioxide per unit of energy?

• Coal

• Oil

• natural gas

• all of these produce the same amount of carbon dioxide.

Which of the following problems is associated with the burning of coal?

• acid rain

• carbon dioxide emissions

• ash with toxic metal impurities

• all of these

Acid rain happens because

• (a) sun leads to heating of upper layer of atmosphere

• (b) burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere

• (c) electrical charges are produced due to friction amongst clouds

• (d) earth atmosphere contains acids

Fuel used in thermal power plants is

• (a) water

• (b) uranium

• (c) biomass

• (d) fossil fuels

Which of the following is a non-renewable source of energy?

• (a) Wood

• (b) Sun

• (c) Fossil fuels

• (d) Wind