The heat change for the following reaction $C_{(s)} + 2S_{(s)} \to CS_{2(l)}$ is known as

For which of the following reactions does the heat of reaction represent the bond energy of $HCl$?

Calculate the standard enthalpy change for the following reaction: $2C_2H_6(g) + 7O_2(g) \rightarrow 4CO_2(g) + 6H_2O(l)$. Given: $\Delta_f H^{\circ}(C_2H_6) = -85 \text{ kJ mol}^{-1}$, $\Delta_f H^{\circ}(CO_2) = -390 \text{ kJ mol}^{-1}$, $\Delta_f H^{\circ}(H_2O) = -285 \text{ kJ mol}^{-1}$. (in $\text{ kJ}$)

For a reaction $A + B + 30 \ kcal \longrightarrow \text{Product}$,the energy of activation of its backward reaction is $50 \ kcal$. The energy of activation of its forward reaction is :-

The enthalpy of combustion of methane,graphite and dihydrogen at $298 \, K$ are $-890.3 \, kJ \, mol^{-1}$,$-393.5 \, kJ \, mol^{-1}$ and $-285.8 \, kJ \, mol^{-1}$ respectively. The enthalpy of formation of $CH_{4(g)}$ will be:
$(i) -74.8 \, kJ \, mol^{-1}$
$(ii) -52.27 \, kJ \, mol^{-1}$
$(iii) +74.8 \, kJ \, mol^{-1}$
$(iv) +52.26 \, kJ \, mol^{-1}$

For the reaction $R \rightarrow P$,the following potential energy diagram is given. What will be the enthalpy change $(\Delta H)$ for the given reaction (in $kJ$)?