Heats of combustion $(\Delta H^o)$ for $C_{(s)}$,$H_{2(g)}$ and $CH_{4(g)}$ are $-94$,$-68$ and $-213 \ kcal/mol$ respectively. The value of $\Delta H^o$ for the reaction,$C_{(s)} + 2H_{2(g)} \to CH_{4(g)}$ is $..... \ kcal$.

If the heat of combustion of $C$ is $-x \, kJ$,the heat of formation of $H_2O$ is $-y \, kJ$,and the heat of combustion of $CH_4$ is $-z \, kJ$,what is the heat of formation of $CH_4$?

Represent the potential energy / enthalpy change in the following processes graphically.
$(a)$ Throwing a stone from the ground to the roof.
$(b)$ $\frac{1}{2} H_{2(g)} + \frac{1}{2} Cl_{2(g)} \rightarrow HCl_{(g)}$
In which of the processes is the potential energy/enthalpy change a contributing factor to the spontaneity?

If $C_{(s)} + O_{2(g)} \longrightarrow CO_{2(g)}; \Delta H = r$ and $CO_{(g)} + \frac{1}{2} O_{2(g)} \longrightarrow CO_{2(g)}; \Delta H = s$,then the heat of formation of $CO$ is

Consider the reaction $2H_2S(g) + 3O_2(g) \rightarrow 2H_2O(l) + 2SO_2(g)$. The magnitude of enthalpy change for the reaction in $\text{kJ mol}^{-1}$ is . . . . . . . (Nearest integer). Given: $\Delta_f H^\circ(H_2S) = -20.1 \text{ kJ mol}^{-1}$,$\Delta_f H^\circ(H_2O) = -286.0 \text{ kJ mol}^{-1}$,$\Delta_f H^\circ(SO_2) = -297.0 \text{ kJ mol}^{-1}$

If standard enthalpy of formation $(\Delta_{f} H^{\circ})$ of $CO_2, H_2 O$ and $CH_4$ are $-393, -286$ and $-74.0 \ kJ \ mol^{-1}$ respectively,the standard enthalpy of combustion of methane in $kJ \ mol^{-1}$ is