Answer: CH3I.
- A CH3I
- B CH3Cl
- C CH3F
- D CH3Br
Correct answer: A. CH3I
Explanation: Boiling point rises with molecular size and van der Waals forces; CH3I has the largest, most polarisable halogen, so it boils highest.
SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.
Concept context
Study carbon-halogen compounds: how they are made, how they react via SN1/SN2 and elimination, their stereochemistry, and their environmental impact.