The bond dissociation energy is highest for

${\mathrm{C}}_2>{\mathrm{Br}}_2>{\mathrm{F}}_2>{\mathrm{I}}_2$Bond dissociation energy of halogen family decreases down the group as the size of atom increases. The decreasing order for the bond dissociation enthalpy of halogen molecules is Cl_2​ 57 kcal/mol>Br₂​ 45.5 kcal/mol>F₂​ 38 kcal/mol> I₂35.6 kcal/mol. A halogen molecule having larger atoms should have low dissociation energy and vice versa. Fluorine is an exception because of interelectronic repulsion is present in small atom fluorine.