A 250 ML Sample of 0

A 25.0 mL sample of 0.150 mol L^-1 hydrazoic acid is titrated with a 0.150 mol L^-1 NaOH solution. What is the pH after 13.3 mL of base is added? The K_a of hydrazoic acid is 1.9 × 10^-5.

A) 4.45
B) 1.34
C) 3.03
D) 4.78
E) 4.66