The decreasing order of bond enthalpies of C-X bond in CH3-F, CH3-Br, CH3-Cl and CH3-I is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → CH3-F, CH3-Cl, CH3-Br, CH3-I
The strength of a carbon–halogen bond depends on how well the orbitals of carbon and the halogen overlap. Going down the group from F to I, the halogen atom gets larger, so the C–X bond gets longer, its orbital overlaps less effectively with the small carbon orbital, and the bond enthalpy decreases.
Shortcut: The C–F bond (smallest halogen) is the strongest and C–I the weakest. Only Option (2) starts with \( \ce{CH3-F} \) and ends with \( \ce{CH3-I} \).
NCERT (2026-27 edition):
Nature of C-X Bond – …
