A solution is prepared by dissolving 0.23 mol of benzoic acid and 0.27 mol of sodium benzoate in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of NaOH to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the NaOH reacts with the _present in the buffer solution. The Ka of benzoic acid is 1.36 x 10-3 A) H20 B) H30+ C) benzoate ion D) benzoic acid E) This is a buffer solution: the pH does not change upon addition of acid or base.