The enthalpies of combustion of cyclohexane $(C_6H_{12})$,cyclohexene $(C_6H_{10})$,and $H_2$ are $-3920, -3800$,and $-241 \, kJ \, mol^{-1}$ respectively. The heat of hydrogenation of cyclohexene is ...... $kJ \, mol^{-1}$.

The molar enthalpies of combustion of $C_2H_{2(g)},$ $C$ (graphite) and $H_{2(g)}$ are $-1300,$ $-394$ and $-286 \ kJ \ mol^{-1},$ respectively. The standard enthalpy of formation of $C_2H_{2(g)}$ is.......$kJ \ mol^{-1}$

Consider the following data :
Heat of formation of $CO_{2(g)} = -393.5 \ kJ \ mol^{-1}$
Heat of formation of $H_2O_{(l)} = -286.0 \ kJ \ mol^{-1}$
Heat of combustion of benzene $= -3267.0 \ kJ \ mol^{-1}$
The heat of formation of benzene is $........... \ kJ \ mol^{-1}$. $(Nearest \ integer)$

From Kirchhoff's equation,which factor affects the heat of reaction?

Compounds with high heat of formation are less stable because

The value of $\Delta H_{O-H}$ is $109 \ kcal \ mol^{-1}$. Then,the formation of one mole of water in the gaseous state from $H_{(g)}$ and $O_{(g)}$ atoms is accompanied by: