The standard enthalpy of formation of carbon monoxide at $298 \ K$ is $-110.5 \ kJ/mol$. The standard internal energy of formation of carbon monoxide at $298 \ K$ and constant volume is ............... $kJ/mol$. (in $.73$)

Calculate the heat of formation of $HCl$ gas from the following reaction: $H_{2(g)} + Cl_{2(g)} \rightarrow 2 HCl_{(g)} ; \Delta H = -194 \ kJ$

Find the value $\Delta H_f^o[NH_{3(g)}]$ if $\Delta H_r$ for the reaction $N_{2(g)} + 3H_{2(g)} \to 2NH_{3(g)}$ is $-\,183.6 \ kJ/mol$ of $N_{2(g)}$.

If the bond dissociation energies of $XY$,$X_2$,and $Y_2$ (all diatomic molecules) are in the ratio of $1 : 1 : 0.5$ and $\Delta_f H$ for the formation of $XY$ is $-200 \ kJ \ mol^{-1}$,the bond dissociation energy of $X_2$ will be in $kJ \ mol^{-1}$:

Given that,$C_{(s)} + O_{2(g)} \longrightarrow CO_{2(g)} ; \Delta H^{\circ} = -x \ kJ \ mol^{-1}$ and $2CO_{(g)} + O_{2(g)} \longrightarrow 2CO_{2(g)} ; \Delta H^{\circ} = -y \ kJ \ mol^{-1}$. The enthalpy of formation of $CO$ will be:

Which of the following statements is correct for the enthalpy of combustion?