Question 16 Explain the following in terms of gain or loss of oxygen with two examples each: (a) Oxidation and (b) Reduction.

(a) Oxidation : The addition of oxygen to a substance is called oxidation. Example : (i) S(s) + O2(g) → SO2(g) (Addition of oxygen to sulphur) (ii) 2Mg(s) + O2 (g) → 2MgO(s) (Addition of oxygen to magnesium) (b) Reduction : The removal of oxygen from a substance is called reduction. Example: (i) CuO + H2 Heat−→−− Cu + H2O Here, copper oxide is being reduced to copper because oxygen gets removed from copper oxide. (ii) ZnO + C → Zn + CO Here, zinc oxide is being reduced to zinc because oxygen gets removed from zinc oxide.