Acid rain:
The moisture or rain water containing harmful acids falls and collects itself in tank, ponds, lakes etc. This is called acid rain. These pollutants due SO2, NO2 etc. dissolves in water.
SO2 + H2O → H2SO4
SO3 + H2O → H2SO4
3NO2 + H2O → 2HNO3 + NO↑
