JEE CHEMISTRY MCQ: THERMODYNAMICS

The standard molar enthalpies of formation of $\mathrm{IF}_3(\mathrm{g})$ and $\mathrm{IF}_5(\mathrm{g})$ are $-470 \mathrm{~kJ}$ and $-847 \mathrm{~kJ},$ respectively. Valence shell electron-pair repulsion theory predicts that $\mathrm{IF}_5(\mathrm{g})$ is square pyramidal in shape in which all $\mathrm{I}-\mathrm{F}$ bonds are equivalent while $\mathrm{IF}_3(\mathrm{g})$ is T-shaped (based on trigonal-bipyramidal geometry) in which $\mathrm{I}-\mathrm{F}$ bonds are of different lengths. It is observed that the axial $\mathrm{I}-\mathrm{F}$ bonds in $\mathrm{IF}_3$ are equivalent to the $\mathrm{I}-\mathrm{F}$ bonds in $\mathrm{IF}_5.$ Calculate the equatorial $\mathrm{I}-\mathrm{F}$ bond strength in $\mathrm{IF}_3.$ Some other details given are as follows.

$\begin{aligned} & \mathrm{I}_2(\mathrm{s}) \rightarrow \mathrm{I}_2(\mathrm{g}): \Delta H=62 \mathrm{~kJ} \\ & \mathrm{F}_2(\mathrm{g}) \rightarrow 2 \mathrm{~F}(\mathrm{g}): \Delta H=155 \mathrm{~kJ} \\ & \mathrm{I}_2(\mathrm{g}) \rightarrow 2 \mathrm{I}(\mathrm{g}): \Delta H=149 \mathrm{~kJ} \end{aligned}$