Chemistry - Halogen Derivative Question with Solution | TestHub

The size of the halogen atom increases in the order $\mathrm{F}<\mathrm{Cl}<\mathrm{Br}<\mathrm{I}$.

As the size of the halogen atom increases, the $\mathrm{C}-\mathrm{X}$ bond length increases.

Bond enthalpy is inversely proportional to bond length. Therefore, the $\mathrm{C}-\mathrm{X}$ bond enthalpy decreases in the order ${\mathrm{CH}}_3-\mathrm{F}>{\mathrm{CH}}_3-\mathrm{Cl}>{\mathrm{CH}}_3-\mathrm{Br}>{\mathrm{CH}}_3-\mathrm{I}$.

Thus, ${\mathrm{CH}}_3-\mathrm{F}$ has the highest bond enthalpy.

Answer: ${\mathrm{CH}}_3-\mathrm{F}$