Determine the $\mathrm{pOH}$ of a solution after 0.1 mole of $\mathrm{NaOH}$ is added to 1 liter of solution containing $0.15 \mathrm{M} {\mathrm{CH}}_3\mathrm{COOH}$ and $0.2 \mathrm{M} {\mathrm{CH}}_3\mathrm{COONa}$. Assume no change in volume. [Given : $\log 3 = 0.48, \log 2 = 0.30$,${}_{\mathrm{p}}\mathrm{K}_{\mathrm{a}}$of acetic acid = 4.74]