Explain the following in terms of the gain of oxygen with two examples each.
(a) Oxidation
(b) Reduction

(a) The element being oxidised is the one to which oxygen is added in a chemical reaction to form the element\’s corresponding oxide.

Example:

O₂(g) + 4K(s) = 2K₂O (s)

O₂ (g) + H₂S = O₂ + SO₂

(b) A compound is said to be reduced in a chemical reaction when the oxygen is removed from it.

Example:

CuO(s) + H₂(g) → Cu(s) + H₂O(l)

2HgO → 2Hg + O₂