A carbonyl compound A(C₄H₈O), which undergoes haloform reaction and gives compound B on reduction. B on heating with sulphuric acid gives a compound C which forms a mono-ozonide D. D on hydrolysis in present of zinc dust gives only acetaldehyde E. 

Identify the compound B.

2-Butanol 

The correct answer is option 2. Butanol.

Since carbonyl compound A(C₄H₈O) undergoes haloform reaction, it must contain the group CH₃CO. Therefore, it is a ketone and must be biutan-2-one.

Since ketone A, i.e., butan-2-one gives compound B on reduction, therefore B must be 2-butanol.