Q48 / 200 · NEET 2021 · Chemistry

The correct sequence of bond enthalpy of ' $\mathrm{C}-\mathrm{X}$ bond is:

  • A
    CH3-F<CH3-Cl<CH3-Br<CH3-I.
  • Correct answer
    B
    CH3-F>CH3-Cl>CH3-Br>CH3-I
  • C
    CH3-F<CH3-Cl>CH3-Br>CH3-I
  • D
    CH3-Cl>CH3-F>CH3-Br>CH3-I

Solution

Bond enthalpy is inversely proportional to the bond length. The bond length order of C-X bond in methyl halides depends on the size of the halogen atom. Bond length order: CH3-F<CH3-Cl<CH3-Br<CH3-I

Hence, bond enthalpy order is

CH3-F>CH3-Cl>CH3-Br>CH3-I

Hence, the correct answer is option: 'B'.

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