Write and explain the order of X—X bond energy for halogen down the group.

Explanation

Enthalpy of dissociation (x-x)/kJ `mol^(-1)`
Cl - Cl gt Br - Br gt F-F gt I-I , Smaller enthalpy of dissociation of `F_2` is due to relatively large electrons electrons repulsion among the lone pairs in `F_2` molecule.