Which of the following Halogens molecules has maximum bond energy?

Explanation

Bond energy( B.E ) is a measure of the bond strength of a chemical bond, and is the amount of energy needed to break the atoms involved in a molecular bond into free atoms. B.E. depends on the atomic radius. Going down the group, in halogens, the bond energy decreases. It is because down the group the distance between the outermost electrons and nucleus decreases, decreasing the force of attraction between them. There is an exception in the halogen group which is of fluorine. This is because the atomic radius of fluorine atoms is so small that when two fluorine atoms form an F-F bond, the internuclear repulsive forces between them reduces the bond strength and thus the bond energy. That is why despite being on the top-most position, fluorine has lower bond energy. Where Chlorine is having the least radius thus, its B.E is the highest among all the members of its group.