Write a brief note on acid rain.

Burning of fossil fuels release oxides of Sulphur, and nitrogen into the air. Nitogen gets oxidized and forms its oxides. These chemicals combine with water and oxygen fall as acid rain on earth in the form of Sulphur and nitric oxides, with water having a pH less than 5. Acid rain reacts with metals & corrodes it, also it reacts with calcium containing substances, therby producing gypsum which then flakes off.