Answer: CH3Cl > CH3F > CH3Br > CH3I.
- A CH3F > CH3Cl > CH3Br > CH3I
- B CH3I > CH3Br > CH3Cl > CH3F
- C CH3Br > CH3Cl > CH3F > CH3I
- D CH3Cl > CH3F > CH3Br > CH3I
Correct answer: D. CH3Cl > CH3F > CH3Br > CH3I
Explanation: Dipole moment reflects bond polarity and bond length together; the measured order is CH3Cl > CH3F > CH3Br > CH3I.
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.