Which of the following on heating with aqueous KOH produces acetaldehyde?

The reaction of CH3CH2Cl with aqueous KOH involves nucleophilic substitution. However, this reaction does not produce acetaldehyde.

CH3CHCl2 on reaction with aqueous KOH undergoes hydrolysis. The reaction proceeds through a carbocation intermediate that undergoes rearrangement to produce acetaldehyde.

CH3CHCl2 + KOH → CH3CH(OH)Cl → CH3CHO + HCl

Therefore, CH3CHCl2 produces acetaldehyde on heating with aqueous KOH.

Hence, option C is correct.