Question

Buffer solution problem: Calculate the pH of a solution that is 0.30 M in HF and 0.15 M in NaF? ...?

Answer 1

For the question given above, I think there is a lack of information such as choice of answer for this question. Here is the solution for the question:
pKa = 3.14
pH = pKa + log [F-] / [HF]
= 3.14 + log 0.15 / 0.30
= 2.84

pH is 2.84. I hope this answer helps.