Explain why,iron sheets are coated with zinc.

Explanation

Iron gets easily rusted in the presence of moist air. Formation of rust `(Fe_(2)O_(3).xH_(2)O)` is a redox reaction in which Fe is oxidised to `Fe^(3+)` ions. Since zinc is more reactive than iron (placed blow iron in the activity series), it is oxidised to `Zn^(2+)` ions instead of iron when coated over the surface of iron. Thus, zinc takes part in the redox reaction while surface of iron remains intact.