Thermochemistry Questions

The standard enthalpy of formation ($\Delta H_f^{\circ }$) at $298\text{K}$ for methane, ${\text{CH}}_4(g)$, is $-74.8{\text{kJ mol}}^{-1}$. The additional information required to determine the average energy for $\text{C}-\text{H}$ bond formation would be:

The standard enthalpy of formation for $\text{ICl}(g)$ is calculated from:${\text{Cl}}_2(g)=2\text{Cl}(g),\Delta H=242.3$${\text{I}}_2(g)=2\text{I}(g),\Delta H=151.0$$\text{ICl}(g)=\text{I}(g)+\text{Cl}(g),\Delta H=211.3$${\text{I}}_2(s)={\text{I}}_2(g),\Delta H=62.76$ Standard states are ${\text{I}}_2(s)$ and ${\text{Cl}}_2(g)$.