Final answer:
A buffer consists of roughly equal amounts of weak conjugate acid/base pair. A buffer maintains constant pH upon addition of any amount of acid or base. A buffer does not necessarily maintain pH 7 upon addition of a reasonable amount of acid or base.
Step-by-step explanation:
A buffer is a solution that maintains a relatively constant pH when an acid or a base is added. It consists of an equilibrium mixture of a weak acid and its conjugate weak base. The buffer capacity depends on the concentrations of the weak acid and its conjugate base. Therefore, statement (a) is true.
Statement (b) is also true. Buffers are designed to resist changes in pH when small amounts of acid or base are added. The presence of the weak acid and its conjugate base helps maintain the pH of the solution.
However, statement (c) is not true. A buffer does not necessarily maintain pH 7 upon addition of a reasonable amount of acid or base. The pH of a buffer depends on the pKa of the weak acid used. The Henderson-Hasselbalch equation can be used to calculate the pH of a buffer solution. So, only statements (a) and (b) are true, making option (d) false.