Calculate the bond enthalpy of Xe –F bond as given in the equation
${\mathrm{XeF}}_4\left(\mathrm{g}\right)\to {\mathrm{Xe}}^{+}\left(\mathrm{g}\right)+{\mathrm{F}}^{-}\left(\mathrm{g}\right)+{\mathrm{F}}_2\left(\mathrm{g}\right)+\mathrm{F}\left(\mathrm{g}\right)$
${\mathrm{\Delta }}_{\mathrm{r}}\mathrm{H}=292\mathrm{K} \mathrm{cal} {\mathrm{mol}}^{-1}$
Ionisation energy of Xe = 279 K cal / mol 
Bond energy (F–F) = 38 Kcal/mol
Electron affinity of F = –85 Kcal/mol