\( (s)\) \( (2s)^2\)
\(K_{sp} = 4s^3\) \(4s^3 = 32 \times 10^{-12} \)
\({s^3} = \frac{{32 \times {{10}^{ - 12}}}}{4} = 8 \times {10^{ - 12}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,s = {(8 \times {10^{ - 12}})^{1/3}} = 2.0 \times {10^{ - 4}}\)
\([O{H^ - }] = 2 \times 2.0 \times {10^{ - 4}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,[O{H^ - }] = 4.0 \times {10^{ - 4}}\,\,pOH = 4 - \log 4\)