Which one of the following orders is not in accordance with the property stated against it ?\

Question

Professor PC Thomas Classes · Answer

(a) : \begin{array}{lcccc} \mathrm{X}-\mathrm{X} 	ext{ bond} & \mathrm{F}-\mathrm{F} & \mathrm{Cl}-\mathrm{Cl} & \mathrm{Br}-\mathrm{Br} & \mathrm{I}-\mathrm{I} \ 	ext{Bond dissociation} & 38 & 57 & 45.5 & 35.6 \ 	ext{energy (kcal/mol)} & & & & \ \end{array} The lower value of bond dissociation energy of fluorine is due to the high inter-electronic repulsions between non-bonding electrons in the $2 p$-orbitals of fluorine. As a result $\mathrm{F}-\mathrm{F}$ bond is weaker in comparison to $\mathrm{Cl}-\mathrm{Cl}$ and $\mathrm{Br}-\mathrm{Br}$ bonds.\