Which factor affects the heat of reaction in the Kirchhoff equation?

The heat of combustion of carbon is $-94 \ kcal$ at $1 \ atm$ pressure. The internal energy of $CO_2$ is .... $kcal$.

At $298 \, K$,the bond energies of $C-H, C-C, C=C$,and $H-H$ are $414, 347, 615$,and $435 \, kJ \, mol^{-1}$ respectively. What will be the enthalpy change for the reaction ${H_2}C=CH_{2(g)} + H_{2(g)} \to H_3C-CH_{3(g)}$ at $298 \, K$ in $kJ \, mol^{-1}$?

The enthalpy change for the reaction $C(s) + O_2(g) \to CO_2(g)$ is:

Explain the standard enthalpy of combustion $\left( \Delta_{c} H^{\theta} \right)$.

The heats of combustion of rhombic and monoclinic sulphur are respectively $70960 \ cal$ and $71030 \ cal$. What will be the heat of conversion of rhombic sulphur to monoclinic? $(cal)$