Observe the following picture write down the chemical reaction with expanation.

Explanation

In the above diagram, process of rusting takes place.
(ii) A certain type of raddish coloured solid layer collects on the metallic surface.
(iii) This layer is called rust.
(iv) Its chemical formula is `Fe_(2)O_(3). xH_(2)O.` The rust is formed by an electrochemical reaction.
(v) Different regions on the surface of iron become anode and cathode.
(vi) Fe is oxidised to `Fe ^(2+)` in hte anode region .
`Fe_((s))to Fe_((aq))^(2+)+2e^(-)`
(vii) `O_(2)` reduces to form water in the cathofe region.
`O_(2(g))+4H_((aq))^(+) +4e^(-) to 2H_(2)O_((l))`
When `Fe^(2+)` ions migrate from the anode region, they react with water and further get oxidised to from `Fe^(3+)` ions.
(viii) A reddish coloured hydrate oxide is formed from `Fe^(3+)` ions, it is called rust. It collects on teh surface.
(ix) `2F_((aq))^(3+) +4H_(2)O_((l))to Fe_(2) O_(3). H_(2)O_((s)) +6H_((aq))^(+).`
(x) Due to various components of atmosphere, oxidation of matals takes place, concequently resulting in their damage.
(xi) This is called Corrosion Iron rusts and a raddish coloured layer is collected on it. This is corrosion of iron.