Bromoethane hydrolyzes faster in water via nucleophilic substitution

Steps:

• Identify reaction: Both undergo hydrolysis with H2O as nucleophile, replacing halogen with OH.
• Determine mechanism: Primary alkyl halides favor SN2 nucleophilic substitution.
• Compare leaving groups: Br⁻ is weaker base than Cl⁻, making it better leaving group.
• Conclude rate: SN2 rate depends on leaving group; bromoethane reacts faster.

Why A is correct:

• Bromoethane has superior Br⁻ leaving group (per leaving group ability trend: I > Br > Cl > F), accelerating SN2 hydrolysis.

Why the others are wrong:

• B: Chloroethane's Cl⁻ is poorer leaving group, so slower hydrolysis.
• C: Mechanism is nucleophilic, not electrophilic substitution (which targets electron-rich centers like aromatics).
• D: Identical to B; chloroethane hydrolyzes slower.

Final answer: A