Why is an iron grill painted frequently? (b) Explain why, though aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.

(a)In order to prevent rusting iron grill is painted frequently.

(b) Aluminium is reactive and forms an oxide layer on its surface when comes to contact with air. That is why there is less corrosion of aluminium when both exposed to air.