A ketone A, which undergoes halform reaction, gives compound B on reduction B on heating with sulphuric acid gives compounds C, which forms mono-ozonide D.D on hydrolysis in the presence of zinc dust gives only acetaldehyde. Identify A, B and C. Write down the reaction involved.

Explanation

Ketone A undergoes haloform reaction. Thus it must contain `CH_(3)CO`-group.
The compound C gives mono-ozonide D, which shows that the compound C contains a double bond. Since, the hydrolysis of D gives only acetaldehyde, the compound C would be as follows `:`
`underset( ( C ) ) (CH_(3) - CH = CH - CH_(3))`
The compound C is obtained by dehydration of the compound B. Hence , the compound B would be
`underset( (B))(CH_(3)-underset( OH ) underset( | ) ( C) H - CH_(2) - CH_(3)`
The compound B is obtained by the reduction of compound A ( which contains `CH_(3)CO` - group ) . Hence, the compound A would be `:`
`underset( ( A ))(CH_(3) - underset( O ) underset( ||)(C) - CH_(2) - CH_(3))`
The reactions involved are as follows `:`