Enthalpy of sublimation of a substance is equal to

The heat of combustion of solid benzoic acid at constant volume is $-321.30 \ kJ$ at $27^{\circ} C$. Its heat of combustion at constant pressure is :

Given that the bond energy of hydrogen-hydrogen bond is $436 \ kJ/mol$,that of hydrogen-oxygen bond is $464 \ kJ/mol$,and those in oxygen molecules $496 \ kJ/mol$,what is the approximate heat of reaction for $2H_2 + O_2 \longrightarrow 2H_2O$ ? .....$kJ/mol$

Match the following allotropes of carbon with their standard enthalpy of formation $(\Delta_f H^{\Theta})$:

Allotrope	$\Delta_f H^{\Theta}$
$i$. Graphite	$b$. $0 \ kJ/mol$
$ii$. Diamond	$c$. $1.90 \ kJ/mol$
$iii$. Fullerene	$a$. $38.1 \ kJ/mol$

The heat of neutralization of $HCl$ by $NaOH$ is $-57.3 \, kJ/mol$. If the heat of neutralization of $HCN$ by $NaOH$ is $-12.1 \, kJ/mol$,then the enthalpy of dissociation of $HCN$ is $...... \, kJ$.

Which of the following reactions represents the standard heat of formation of the product?