Corrosion of iron is essentially an electrochemical phenomeonon where the cell reaction are

Options

A. Fe is oxidised to `Fe^(3+)` and `H_(2)O` is reduced to `O_(2)^(2-)`
B. Fe is oxidised to `Fe^(2+)` and `H_(2)O` is reduced to `O_(2)^(2-)`
C. Fe is oxidised to `Fe^(2+)` and `H_(2)O` is reduced to `O_(2)`
D. Fe is oxidised to `Fe^(2+)` and `H_(2)O` is reduced to `O_(2)`

Answer

D

Explanation

`Fe rarr Fe^(2+) +2e^(-)`
`O_(2) +2H_(2)O+4e^(-) rarr 4OH^(-)`
The overall reaction is
`2Fe+O_(2) +2h_(2) rarr2Fe(OH)_(2)`
`Fe(OH)_(2)` may be dehydrated to iron oxide FeO or further oxidised to `Fe(OH)_(3)` and then dehydrated to iron rust `Fe_(2)O_(3)`