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

Oxidation is gain of oxygen.
2H₂ + O₂ → 2H₂O
The hydrogen is oxidized and the oxygen is reduced.
N₂ + O₂ → 2NO
This formation of nitric oxide oxidizes the nitrogen and reduces the oxygen.
Reduction is the loss of oxygen from a substance. For example, copper oxide can be reduced to form copper if it is reacted with hydrogen:
CuO + H₂ → Cu + H₂O
Zinc oxide can be reduced to zinc metal if heated with carbon.
ZnO + C → Zn + CO