Which of these statements is true?

a. if you add a strong acid or base to a buffer, the buffer's pKa or pKb will change
b. To do calculations in which strong acid or base is added to a buffer, you only need to use the Henderson-Hasselbalch equation.
c. If you add strong acid or base to a buffer, the pH will never change.
d. Strong bases react with strong acids, but not with weak acids.
e. To do calculations in which strong acid or base is added to a buffer, you need to calculate the amounts of substances from the neutralization reaction and then equilibrate.

The correct answer is 'e'

Explanation:

Buffer is a solution that has the ability to resist any change in pH when a small amount of an acid or a base is added to it. It contains a weak acid and its conjugate base or a weak base and its conjugate acid.

a)addition of a strong acid or a strong base will not bring about any changes in its ka or kb values hence pka and pkb will also not change.Thus the first statement is false.

b)Along with Henderson-Hasselbalch equation,stoichiometric calculations are also carried out,so this statement is "false" too.

c)addition of a strong acid or base to a buffer will bring about a little change in pH,so this statement is also false.

d)Strong base does react with weak acids(as well as strong acid).Because strong acids and strong base are both consumed by the reaction with the buffer.Hence this statement is also false.

e)This statement is true because when a strong acid or base is added to a buffer,there will be a change in the amount of product produce after neutralization between the buffer and its weak components,hence this change has to be calculated and then equilibrated.