Haloalkane structure determines hydrolysis mechanism

Steps:

• Examine structures: P is tertiary haloalkane (three alkyl groups on carbon with halogen); Q is primary (one alkyl group).
• Recall SN1 mechanism favored for tertiary halides due to stable carbocation formation; SN2 for primary due to backside attack without carbocation.
• Hydrolysis of P proceeds via SN1 as rate depends only on alkyl halide concentration.
• Hydrolysis of Q proceeds via SN2 as rate depends on both alkyl halide and nucleophile concentrations.

Why A is correct:

• P is tertiary, so undergoes SN1 hydrolysis per the rule that 3° halides form stable 3° carbocations, accelerating unimolecular rate-determining step.

Why the others are wrong:

• B: P (tertiary) cannot undergo SN2; steric hindrance blocks backside attack.
• C: Q (primary) favors SN2, not SN1; primary carbocation is unstable.
• D: Q undergoes SN2, but A correctly identifies P's mechanism; question seeks the specified correct row.

Final answer: A