Question

part c buffers work best when ... the ph is nearly neutral. nearly all of the buffer molecules are undissociated. about half of the buffer molecules are dissociated. nearly all of the buffer molecules are dissociated. the ratio of h⁺ to oh⁻ is close to 1.0. part d how does the way a buffer stabilizes ph during addition of acid differ from the way the same buffer stabilizes ph? in one case it adds h⁺, in the other case it adds oh⁻ the same buffer cant work for both acid and base in one case the buffer is strong, in the other case its weak

Explanation:

Buffers consist of a weak - acid and its conjugate base (or vice - versa). They work best when about half of the buffer molecules are dissociated. This allows the buffer to effectively react with both added acids (the conjugate base will react with $H^+$) and added bases (the weak acid will react with $OH^-$). If nearly all are undissociated or nearly all are dissociated, the buffer's ability to resist pH changes is limited. The pH of the buffer system doesn't have to be neutral, and the ratio of $H^+$ to $OH^-$ being close to 1.0 is not the key factor for buffer effectiveness.

Answer:

about half of the buffer molecules are dissociated