Question

Which of the following has the highest bond energy ?

• A. Fluorine
• B. Bromine
• C. Iodine
• D. Chlorine

Answer 1

Answer: (D)

Bond energy of Fluorine (although $F_2$ has smallest bond length) is lesser than $C{l}_2$ and $B{r}_2$ due to greater interelectronic repulsions between the lone pair of electrons on F atom.
Halogen F - F Cl - Cl Br - Br I - I
Bond dissociation 38 57 45.5 35.5
energy (kcal/mol)
So chlorine has highest bond energy.