Explain the following in terms of gain or loss of oxygen with two examples each.

(a) Oxidation

(b) Reduction

(a) Oxidation is gain of oxygen by a substance.

For example,

1. Copper is oxidised to Copper oxide:
   2Cu + O₂ $\xrightarrow{\text{Heat}}$ 2CuO

2. Carbon is oxidised to Carbon dioxide
   C + O₂ ⟶ CO₂

(b) Reduction is loss of oxygen from a substance.

For example,

1. Copper (II) oxide is reduced to Copper
   CuO + H₂ $\xrightarrow{\text{Heat}}$ Cu + H₂O

2. Zinc (II) oxide is reduced to Zinc.
   ZnO + C ⟶ Zn + CO