Calculate the pH of the solution when $0.1\; M\; CH_3 COOH (50 ml)$ and $0.1\; M\; NaOH (50 ml)$ are mixed, $[Ka (CH_3COOH)=10^{-5}]$

Question

$\begin{array}{1 1} (a)\;9.65 \\ (b)\;7.07 \\ (c) \;8.85 \\ (d)\;6.75 \end{array}$