Which of the following heat of reaction expresses the bond energy of $HCl$?

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 $...... \, kJ$.

In the reaction $H_2 + Cl_2 \rightarrow 2HCl$,heat is released. The bond energies of $H-H$ and $Cl-Cl$ are $430 \ kJ \ mol^{-1}$ and $242 \ kJ \ mol^{-1}$ respectively. If the enthalpy of reaction is $-182 \ kJ \ mol^{-1}$,the bond energy of $H-Cl$ is . . . . . . $kJ \ mol^{-1}$.

Which of the following substances has the highest value of standard molar enthalpy of formation at $298 \ K$?

One mole of ethanol $(l)$ was completely burnt in oxygen to form $CO_{2(g)}$ and $H_2O_{(l)}$. What is the $\Delta_r H^{\ominus}$ (in $kJ \ mol^{-1}$) for this reaction?
(The standard enthalpy of formation $(\Delta_f H^{\ominus})$ of $C_2H_5OH_{(l)}$,$CO_{2(g)}$ and $H_2O_{(l)}$ is respectively $-277, -393$ and $-286 \ kJ \ mol^{-1}$.)

The heat change for the reaction $H_2 + \frac{1}{2} O_2 \to H_2 O$ is called