Consider a solution of a weak acid at a pH equal to its pKa. By how much would the pH change, and in which direction, if we added to this solution

Consider a solution of a weak acid at a pH equal to its pKa. By how much would the pH change, and in which direction, if we added to this solution enough base to neutralize 10% of the total acid?Answer0.18, lower0.10, higher0.10, lower0.40, higher0.18, higher