Final answer:
For a buffer with a pH of 8.10, the best choice is hypochlorous acid (HClO) with a pKa of 7.54, as it is closest to the target pH and falls within the optimal buffering range.
Step-by-step explanation:
To create a buffer with a pH of 8.10, we need to select an acid and its conjugate base with a pKa value close to the desired pH. According to the Henderson-Hasselbalch equation, a buffer has an optimal pH when the concentrations of the weak acid and its conjugate base are similar, and this is usually when the pKa is close to the target pH. Looking at the given options, the acid with the pKa value closest to 8.10 is HClO with a pKa of 7.54 and HCN with a pKa of 9.31. Between these two, HClO is more appropriate for making a buffer with a pH of 8.10 because its pKa value is closer to the desired pH and it lies within the effective buffering range, typically within one pH unit of the acid's pKa value. Using an acid like HClO2 with a pKa of 1.96 or HC6H8O4 with a pKa of 4.41 would not be effective, as their pKa values are much lower than the desired pH, and using H2CO3 with a pKa of 6.37 would also be less effective since it's not as close to the pH of 8.10 as HClO is.