Explain why Bond dissociation energy of `F_2` is less than that of `Cl_2` ?

Explanation

Fluorine atom being smaller in size, the inter-electronic repulsions between the non-bonding electrons present in the 2p-orbitals of fluorine atoms are much larger than similar interelectronic repulsions between the non-bonding electrons present in the relatively larger 3p-orbitals of chlorine atoms.