The standard enthalpies of formation of $CO$ and $CO_2$ are $-110 \, kJ \, mol^{-1}$ and $-394 \, kJ \, mol^{-1}$ respectively. What will be the heat of combustion of $1 \, mol$ of graphite in $kJ$?

For the reaction $\frac{1}{2} X_2O_{(s)} \to X_{(s)} + \frac{1}{4} O_{2(g)}$ with $\Delta H = 90 \ kJ$,the enthalpy change for the reaction of $1 \ mol$ of $O_2$ with metal $X$ is ................ $kJ$.

If standard enthalpy of formation $(\Delta_{f} H^{\circ})$ of $CO_2, H_2 O$ and $CH_4$ are $-393, -286$ and $-74.0 \ kJ \ mol^{-1}$ respectively,the standard enthalpy of combustion of methane in $kJ \ mol^{-1}$ is

If the standard enthalpies of formation of hydrazine and water are $+50.6 \, kJ/mol$ and $-285.9 \, kJ/mol$ respectively,calculate the $\Delta H$ for the following reaction: $N_2H_{4(g)} + O_{2(g)} \to N_{2(g)} + 2H_2O_{(l)}$ in $kJ \, mol^{-1}$.

If the enthalpy of atomisation for $Br_{2(l)}$ is $x \ kJ/mol$ and the bond enthalpy for $Br_{2(g)}$ is $y \ kJ/mol$,what is the relation between them?

The heat of formation of methane $C_{(s)} + 2H_{2(g)} \to CH_{4(g)}$ at constant pressure is $-18500 \ cal$ at $25 \ ^oC$. The heat of reaction at constant volume would be (in $cal$)