A compound (A) with molecular formula $C_4{H}_{10}O$ on oxidation forms compound (B). The compound (B) gives positive iodoform test. Compound (B) on reaction with ${\mathrm{CH}}_3\mathrm{MgBr}$ followed by hydrolysis gives (C). Identify (A) to (C) and give the sequence of reactions.

Since (B) gives positive iodoform test it must be a methyl ketone. The only methyl ketone with four C-atoms is butanone ${\mathrm{CH}}_3{\mathrm{COCH}}_2{\mathrm{CH}}_3$.

Butanone will be obtained by oxidation of butan-2-ol. Therefore, compound (A) is butan-2-ol ${\mathrm{CH}}_3\mathrm{CH}\left(\mathrm{OH}\right){\mathrm{CH}}_2{\mathrm{CH}}_3$. Butanone on reaction with ${\mathrm{CH}}_3\mathrm{MgBr}$ followed by hydrolysis gives a $3^0$ alcohol,