Answer:
C
Explanation:
The Henderson-Hasselbalch equation relates pH to the concentrations of an weak acid-base conjugate pair as follows:
pH = pKa + log([A⁻]/[HA])
For solution 1, the pH may be expressed as follows:
pH = pKa + log(5.0M/5.0M) = pKa
For solution 2, pH may be expressed as follows:
pH = pKa + log(0.050M/0.050M) = pKa
Thus, the pH values are equal to the pKa in both cases and are the same.