K_a for butyric acid ( C_3 H_7 COOH ) is 2 × 10^-5. The pH of 0.2 M solution of butyric acid is \ \ \ \ × 10^-1. (Nearest integer) [Given log 2=0.30 ]

$\displaystyle \mathrm{K}_{\mathrm{a}}$ for butyric acid $\displaystyle \left(\mathrm{C}_3 \mathrm{H}_7 \mathrm{COOH}\right)$ is $\displaystyle 2 \times 10^{-5}$. The pH of $\displaystyle 0.2$ M solution of butyric acid is \_\_\_\_ $\displaystyle \times 10^{-1}$. (Nearest integer) [Given $\displaystyle \log 2=0.30$ ]