A Solution Is Prepared by Dissolving 0 $K _ { a }$

Multiple Choice

A solution is prepared by dissolving 0.23 mol of formic acid and 0.27 mol of sodium formate in water sufficient to yield 1.00 L of solution.The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly.The pH does not decrease drastically because the HCl reacts with the ________ present in the buffer solution.The $K _ { a }$ of formic acid is 1.36 × 10^-3.

A) H₂O
B) $\mathrm{H}_{3} \mathrm{O}^{+}$
C) formate ion
D) formic acid
E) This is a buffer solution: the pH does not change at all upon addition of acid or base.