Applications Of Equilibrium Constants

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 ____ × 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

In an experiment, moles of was placed in a one-litre flask and the concentration of after equilibrium established, was found to be mol/ L. The equilibrium constant at is ____ .