Calculate the PH of the Solution Resulting from the Addition

Multiple Choice

Calculate the pH of the solution resulting from the addition of 75.0 mL of 0.15 M KOH to 35.0 mL of 0.20 M HCN (K_a (HCN) = 4.9 × 10^-10) .

A) 9.31
B) 9.18
C) 9.52
D) 11.63
E) 12.59