Buffer solutions are solutions that resist changes in pH when small amounts of acid or base are added to them. They are typically composed of a weak acid and its conjugate base or a weak base and its conjugate acid. The ability of a buffer solution to maintain its pH depends on the presence of both the weak acid or base and its conjugate pair.

When a weak base is added to a buffer solution, the buffer is destroyed. This is because the weak base reacts with the weak acid present in the buffer to form their respective conjugate acid and base. This reaction consumes the weak acid and weak base, disrupting the balance of the buffer system. As a result, the pH of the solution will change significantly, and the buffer will no longer be able to resist changes in pH.

The addition of a strong acid or base does not necessarily destroy a buffer solution. Strong acids and bases are completely dissociated in water and do not have conjugate pairs. Therefore, they do not participate in the buffer system. Instead, they directly change the concentration of hydrogen ions (H+) or hydroxide ions (OH-) in the solution, leading to a significant change in pH.

The addition of a weak acid to a buffer solution does not necessarily destroy the buffer. The weak acid will simply increase the concentration of its conjugate base, helping to maintain the buffer system.

The addition of a salt to a buffer solution also does not destroy the buffer. Salts are composed of cations and anions, and their presence does not significantly affect the buffer system as long as they do not react with the weak acid or base.

In summary, the buffer solution is destroyed when a weak base is added because it reacts with the weak acid in the buffer, disrupting the balance of the buffer system. The addition of a strong acid or base, weak acid, or salt does not destroy the buffer.