A PH 488 Buffer Was Prepared by Dissolving 0

Multiple Choice

A pH 4.88 buffer was prepared by dissolving 0.10 mol of benzoic acid (K_a = 6.3 × 10^-5) and 0.50 mol of sodium benzoate in sufficient pure water to form a 1.00 L solution.To a 70.0 mL aliquot of this solution was added 2.00 mL of 2.00 M aqueous HI solution.What was the pH of the new 72.0 mL solution?

A) 2.84
B) 3.16
C) 3.36
D) 4.65
E) 4.90