The bond energies of $H-H$ and $Cl-Cl$ are $430 \, kJ/mol$ and $240 \, kJ/mol$ respectively. If $\Delta_f H$ for $HCl$ is $-90 \, kJ/mol$,then the bond enthalpy of $HCl$ will be ...... $kJ/mol$.

$H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}$; $\Delta H$ at $298 \ K = -285.8 \ kJ$. The molar enthalpy of vaporization of water at $1 \ atm$ and $25^{\circ}C$ is $44 \ kJ$. The standard enthalpy of formation of $1 \ mole$ of water vapor at $25^{\circ}C$ is $...... \ kJ$. (in $.8$)

Given
$N_{2(g)} + 3H_{2(g)} \longrightarrow 2NH_{3(g)} \quad \Delta_{r}H^{\theta} = -92.4 \, kJ \, mol^{-1}$
What is the standard enthalpy of formation of $NH_{3}$ gas?

Which of the following equations correctly represents the standard heat of formation $(\Delta H_f^o)$ of methane?

What will be the heat of formation of methane,if the heat of combustion of carbon is $-x \ kJ$,heat of formation of water is $-y \ kJ$ and heat of combustion of methane is $z \ kJ$?

Carbon and carbon monoxide burn in oxygen to form carbon dioxide according to the following reactions:
$C(s) + O_2(g) \to CO_2(g)$; $\Delta H = -394 \ kJ \ mol^{-1}$
$2CO(g) + O_2(g) \to 2CO_2(g)$; $\Delta H = -569 \ kJ \ mol^{-1}$
The heat of formation of $1 \ mol$ of carbon monoxide is thus ..... $kJ \ mol^{-1}$.