What is corrosion? Describe the electrochemical phenomenon of rusting of iron

Explanation

Corrosion is the process of slowly eating away of the metal due to attack of the atmospheric gases on the surface of the metal resulting into the formation of compounds such as oxides, sulphides, carbonate, etc. the corrosion of iron is called rusting. Accrording the theory of rusting impure iron surface behaves as a small electrochemical cell in the presence of water containing dissolved oxygen or `CO_(2)`.