A solution is prepared by dissolving 0.23 mol of nitrous acid and 0.27 mol of sodium nitrite 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 Ka of nitrous acid is 1.36 × 10-3.A) H2OB) H3O+C) nitrite ionD) nitrous acidE) This is a buffer solution: the pH does not change upon addition of acid or base.