A pH 4.88 buffer was prepared by dissolving 0.10 mol of benzoic acid (Ka = 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?
◦ 2.84
◦ 3.16
◦ 3.36
◦ 4.65
◦ 4.90