What is the ${\mathrm{P}}^{\mathrm{H}}\mathrm{of} \mathrm{a} \mathrm{buffer} \mathrm{containing}$0.09 M ${\mathrm{CH}}_3\mathrm{COOH}$ and 0.15 M of potassium acetate? $\left[{\mathrm{K}}_{\mathrm{a}}=1.8\times {10}^{-5}, \log 5=0.699, \log 3 =0.4771, \log 1.8=0.2553\right]$

• A

  4.97

• B

  4.70

• C

  7.04

• D

  3.40