Propan-2-ol is obtained when $\mathrm{CH}{}_3\mathrm{MgBr}$ is treated with which carbonyl compound, followed by $\mathrm{H}{}_3\mathrm{O}{}^{+}$?

Grignard reagents give a secondary alcohol with any aldehyde other than methanal. $\mathrm{CH}{}_3\mathrm{MgBr}$ adds to $\mathrm{CH}{}_3\mathrm{CHO}$ to give $\mathrm{CH}{}_3-\mathrm{CH}(\mathrm{OMgBr})-\mathrm{CH}{}_3$, which on hydrolysis gives propan-2-ol. $\mathrm{HCHO}$ gives ethanol, acetone gives 2-methylpropan-2-ol and the ester gives 2-methylpropan-2-ol.