$$p{K_a}$$  of a weak acid $$(HA)$$  and $$p{K_b}$$  of a weak base $$(BOH)$$  are 3.2 and 3.4, respectively. The $$pH$$ of their salt $$(AB)$$  solution is

Solution :
The salt $$(AB)$$  given is a salt is of weak acid and weak base. Hence its pH can be calculated by the formula
$$\eqalign{ & \therefore pH = 7 + \frac{1}{2}p{K_a} - \frac{1}{2}p{K_b} \cr & = 7 + \frac{1}{2}\left( {3.2} \right) - \frac{1}{2}\left( {3.4} \right) \cr & = 6.9 \cr} $$