Hydrolysis of geminal dihalide starts with substitution

Steps:

• Identify reactant: CH3CH2CHCl2 is a geminal dihalide with two Cl on the same carbon.
• Note reagent: Aqueous NaOH provides OH- as a nucleophile for attack.
• Determine first step: OH- displaces one Cl- via SN1 or SN2, forming CH3CH2CH(OH)Cl.
• Confirm mechanism: This halogen replacement defines substitution.

Why D is correct:

• Substitution involves nucleophilic attack replacing Cl with OH, as in R-X + OH- → R-OH + X-.

Why the others are wrong:

• A: Addition occurs across double/triple bonds, absent in saturated dihalide.
• B: Elimination removes HX to form alkenes, but product is aldehyde, not alkene.
• C: Oxidation requires oxidizing agents like KMnO4; here, first step adds OH without electron loss.

Final answer: D