Give the composition, causes and effects of acid rain.

Composition
Acid rain results from acids like nitric acid and sulphuric acid present in polluted air. These acids are formed when oxides of nitrogen and sulphur come into contact with rain water.

Causes
Fossil fuels contain compounds of nitrogen and sulphur in addition to carbon. Due to combustion of these fuels, large amounts of sulphur dioxide, oxides of nitrogen and carbon dioxide get discharged into the atmosphere. These oxides dissolve in rainwater to form mineral acids which is the main cause of acid rain.

Effects

1. Acid rain affects soil chemistry. It removes calcium and potassium, both the basic ingredients of soil, thus making it lose its fertility.
2. Acid rain causes nutrient loss from plants thus damaging their leaves.
3. The water of lake and rivers is gradually becoming acidic due to acid rain, which is affecting aquatic life.
4. Acid rain causes extensive damage to building and sculptural materials like marble, limestone, slate, mortar, etc. These materials become pitted and thus weaken mechanically.
5. Acid rain increases corrosion of metals.
6. In high concentrations, it affects a person's breathing. In lower concentrations, it injures lung tissues.