Question

William finds a piece of pure iron in his garden. After a few days the iron begins to rust what are two types of substances involved in the rusting process of iron

Answer 1

Answer: Iron is an element as it contains only one kind of atom, which combines with the oxygen from the air to produce rust, that is, iron oxide. The rust comprises two kinds of atoms, which signifies that it is a compound.

Explanation:

... In the case, iron oxide is a compound as it comprises Fe and O atom.