What is corrosion ? Describe the role of zinc in cathodic protection of iron. Can we use tin in place of zinc for this purpose ? Give reason.

Explanation

Corrosion is a process in which a metal reacts with substances present in the atmosphere to form compounds at its surface.
Role of zinc : Zn acts as anode. It loses electrons in preference to iron because it is more reactive than Fe.
`Zn to Zn^(2+) + 2e^(-)`
If any `Fe^(2+)` ions are formed, they gain electrons to form iron back.
`Fe^(2+) + 2e^(-) to Fe`
Tin cannot be used to protect iron because it is lesser reactive than Fe.