The standard enthalpy of formation $\left({\mathrm{\Delta }}_{\mathrm{f}}{H}^{\circ }\right)$ at 298 K for methane, ${\mathrm{CH}}_4\left(\mathrm{g}\right)$, is $-78.4\mathrm{kJ}{\mathrm{mol}}^{-1}$. The additional information required to determine the average for $\mathrm{C}-\mathrm{H}$ bond formation would be

The given information is $\mathrm{C}\text{ (graphite) }+2{\mathrm{H}}_2\left(\mathrm{g}\right)⟶{\mathrm{CH}}_4\left(\mathrm{g}\right); {\mathrm{\Delta }}_{\mathrm{f}}{H}^{\circ }=-74.84\mathrm{kJ}{\mathrm{mol}}^{-1}$

To determine the average energy of $\mathrm{C}-\mathrm{H}$ we refer to the reaction ${\mathrm{CH}}_4\left(\mathrm{g}\right)⟶\mathrm{C}\left(\mathrm{g}\right)+4\mathrm{H}\left(\mathrm{g}\right)$

Hence, in addition to  ${\mathrm{\Delta }}_{\mathrm{f}}{H}^{\circ }\left({\mathrm{CH}}_4\right)$, we must have data on the dissociation energy of ${\mathrm{H}}_2$ and enthalpy of sublimation of carbon.