Which one of the following arrangement does not give the correct picture of the trends indicated against it?

F₂ > Cl₂ > Br₂ > I₂ : Oxidising power

F₂ > Cl₂ > Br₂ > I₂ : Electron gain enthalpy

F₂ > Cl₂ > Br₂ > I₂ : Bond dissociation energy

F₂ > Cl₂ > Br₂ > I₂ : Electronegativity

Answer

F₂ > Cl₂ > Br₂ > I₂ : Bond dissociation energy

Generally, bond dissociation energies decrease in a group. Bond dissociation energy also decreases with repulsion.

X-X Bond	F-F	Cl-Cl	Br- Br	I-I
Bond length (A)	1.42	1.99	2.28	2.67
Bond dissociation energy (kcal/mol)	38	57	45.5	35.6

In general, the bond dissociation energy decreases as the bond length increases, but the bond dissociation energy of F₂ is less than that of Cl₂. It is due to greater interelectronic repulsion between the lone pair of electrons on the two bonded fluorine atoms. Hence, the order of bond dissociation energy is as:
Cl₂ > Br₂ > F₂ > I₂