Question

Aluminium is more reactive than iron yet there is less corrosion of alumnium when both are exposed to air

Answer 1

because as soon as aluminium comes in contact with air it forms a later of aluminium oxide which prevents its further corrosion whereas iron reacts slowly and then gets corroded

Answer 2

Aluminium forms a protective layer of aluminium oxide over it when exposed to air , which protects it from being corroded . That is why aluminium  corrodes less when iron and aluminium both are exposed to air .

HOPE IT HELPS YOU . ; )