Acid rain is caused by the pollution of the environment by –

Acid rain is caused by the pollution of the environment by primarily sulphur dioxide and nitrogen oxides.

These pollutants are released into the atmosphere during the burning of fossil fuels, like coal, for electricity generation and from the exhaust of vehicles.

When they reach the atmosphere, they react with water, oxygen, and other chemicals to form sulphuric and nitric acid, which fall back to Earth as acid rain.