The $H-H$ bond energy is $430 \ kJ \ mol^{-1}$ and $Cl-Cl$ bond energy is $240 \ kJ \ mol^{-1}$. $\Delta H$ for the formation of $HCl$ is $-90 \ kJ \ mol^{-1}$. The $H-Cl$ bond energy is about:

At $300 \, K$,the standard enthalpies of formation of $C_6H_5COOH_{(s)}$,$CO_{2_{(g)}}$,and $H_2O_{(l)}$ are $-408$,$-393$,and $-286 \, kJ \, mol^{-1}$ respectively. What is the heat of combustion of benzoic acid at constant volume in $kJ$ (in $.75$)? $(R = 8.31 \, J \, mol^{-1} \, K^{-1})$

Which of the following reactions is exothermic?

The formation enthalpies,$\Delta H_{f}^{\ominus}$ for $H_{(g)}$ and $O_{(g)}$ are $220.0$ and $250.0 \ kJ \ mol^{-1}$,respectively,at $298.15 \ K$,and $\Delta H_{f}^{\ominus}$ for $H_2O_{(g)}$ is $-242.0 \ kJ \ mol^{-1}$ at the same temperature. The average bond enthalpy of the $O-H$ bond in water at $298.15 \ K$ is $.......... \ kJ \ mol^{-1}$ (nearest integer).

The standard enthalpies of formation of $CO_{2(g)}$,$H_2O_{(\ell)}$ and glucose$_{(s)}$ at $25^{\circ} C$ are $-400 \ kJ/mol$,$-300 \ kJ/mol$ and $-1300 \ kJ/mol$,respectively. The standard enthalpy of combustion per gram of glucose at $25^{\circ} C$ is

If enthalpies of formation of $C_2H_{4(g)}$,$CO_{2(g)}$ and $H_2O_{(l)}$ at $25 \ ^\circ C$ and $1 \ atm$ pressure are $52$,$-394$ and $-286 \ kJ \ mol^{-1}$ respectively,the enthalpy of combustion of $C_2H_{4(g)}$ will be.....$kJ \ mol^{-1}$.