Final answer:
Hydrofluoric acid, with the highest pKa value among the given options, would produce a buffer with the highest pH when mixed with its conjugate base in equal portions.
Step-by-step explanation:
A buffer is a solution that resists changes in pH when a small amount of acid or base is added. It is composed of a weak acid and its conjugate base in roughly equal proportions. In order to determine which of the given acids would produce a buffer with the highest pH when mixed with its conjugate base in equal portions, we need to compare their pKa values. The pKa of a weak acid is a measure of its acidity, with a lower value indicating a stronger acid. The acid with the highest pKa value (weakest acid) will produce the buffer with the highest pH.
Looking at the given options, hydrofluoric acid (HF) has a pKa value of 3.18, which is the highest among the options. Therefore, when mixed with its conjugate base in equal portions, hydrofluoric acid would produce a buffer with the highest pH.