If the standard enthalpy change $\left(\Delta_{r} H^\theta\right)$ for the reaction $H_{2(g)} + Br_{2(l)} \rightarrow 2 HBr_{(g)}$ is $-72.8 \ kJ$,the standard enthalpy of formation $\left(\Delta_{f} H^\theta\right)$ of $HBr_{(g)}$ (in $kJ \ mol^{-1}$) is

$AB$,$A_2$,and $B_2$ are diatomic molecules. Enthalpies of dissociation of $AB$,$A_2$,and $B_2$ are in the ratio of $1:1:0.5$. Enthalpy of formation of $AB$,$\Delta_f H = -100 \ kJ \ mol^{-1}$. Find the dissociation enthalpy of $A_2$?
Reaction : $\frac{1}{2} A_2 + \frac{1}{2} B_2 \to AB$

The heats of combustion of carbon and carbon monoxide are $-394 \, kJ \, mol^{-1}$ and $-285 \, kJ \, mol^{-1}$ respectively. Find the heat of formation of $CO$ in $kJ \, mol^{-1}$.

Which of the following is an endothermic reaction?

Heat of combustion of two isomers $x$ and $y$ are $17 \ kJ/mol$ and $12 \ kJ/mol$ respectively. From this information,it may be concluded that:

The heat of combustion of $C$,$S$ and $CS_2$ are $-393.3 \ kJ$,$-293.7 \ kJ$ and $-1108.76 \ kJ$ respectively. What will be the heat of formation of $CS_2$ in $kJ$?