50 mL of 0.1 M CH₃COOH is being titrated against 0.1 M NaOH. When 25 mL of NaOH has been added, the pH of the solution will be _____________ $$\times$$ 10^$$-$$2. (Nearest integer)

(Given : pK_a (CH₃COOH) = 4.76)

log 2 = 0.30

log 3 = 0.48

log 5 = 0.69

log 7 = 0.84

log 11 = 1.04

The molar solubility of Zn(OH)₂ in 0.1 M NaOH solution is x $$\times$$ 10^$$-$$18 M. The value of x is _________ (Nearest integer)

(Given : The solubility product of Zn(OH)₂ is 2 $$\times$$ 10^$$-$$20)

The pH of a solution obtained by mixing 50 mL of 1 M HCl and 30 mL of 1 M NaOH is x $$\times$$ 10^$$-$$4. The value of x is ____________. (Nearest integer) [log 2.5 = 0.3979]

A₃B₂ is a sparingly soluble salt of molar mass M (g mol^$$-$$1) and solubility x g L^$$-$$1. The solubility product satisfies $${K_{sp}} = a{\left( {{x \over M}} \right)^5}$$. The value of a is _____________. (Integer answer)