Calculate the enthalpy change when $12 \ g$ of carbon reacts with sufficient hydrogen to form methane. If the enthalpy of formation of methane is $-75 \ kJ \ mol^{-1}$. (in $kJ$)

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

If $3.365 \text{ g}$ of ethanol $(l)$ is burnt completely in a bomb calorimeter at $298.15 \text{ K}$, the heat produced is $99.472 \text{ kJ}$. The $|\Delta H_f^\circ|$ of ethanol at $298.15 \text{ K}$ is . . . . . . $\times 10^2 \text{ kJ mol}^{-1}$.

Energy required to dissociate $16 \ g$ of $O_{2(g)}$ into free atoms is $x \ kJ$. The value of bond enthalpy of $O=O$ bond is

The heat of formation of methane $C_{(s)} + 2H_{2(g)} \to CH_{4(g)}$ at constant pressure is $-18500 \ cal$ at $25 \ ^oC$. The heat of reaction at constant volume would be (in $cal$)

Given the following thermochemical equations:
$(i)$ $H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(l)}; \Delta H = -285 \text{ kJ}$
$(ii)$ $N_2O_{5(g)} + H_2O_{(l)} \rightarrow 2HNO_{3(l)}; \Delta H = -76.6 \text{ kJ}$
$(iii)$ $N_{2(g)} + 3O_{2(g)} + H_{2(g)} \rightarrow 2HNO_{3(l)}; \Delta H = -348.2 \text{ kJ}$
Calculate the $\Delta H$ for the reaction: $2N_{2(g)} + 5O_{2(g)} \rightarrow 2N_2O_{5(g)}$. (in $\text{ kJ}$)