Question

Why an iron rod exposed to moisture and air loses its lustre

Answer 1

when iron reacts with water and air it creates an reaction of 4Fe+3O²-2Fe²2O³. which leads to corroding of iron forming a new substance.. so that it loses its lustrousness.

Answer 2

It is the effect of air and moisture. Metals like iron,aluminium etc reacts with moist air and get oxidized and they lost their shine. Parts of air like hydrogen sulphide, sulphur, carbonates reacts with metals like silver (reacts with hydrogen sulphide to form silver sulphide) and copper (reacts with sulphur to form copper sulphate) which causes dullness.