Question

Among the halogens which has weakest bond energy?

(a) Br₂

(b) Cl₂

(c) F₂

(d) I₂ 

Answer 1

Correct option is: (d) I₂ 

Lesser the bond energy, weaker is the bond. Thus, I - I bond with lowest bond energy (151kJmol⁻¹) is the weakest bond.

Answer 2

The right option is (d) because it is the largest halogen in the 17th group.So, nucleus of both atoms are located comparatively far from each other.  Hence, the relative force of attraction between the nuclei of two iodine atoms is less as compared to other  Halogens in the group making the bond between them weak. So, less bond energy