The $\Delta_{f} H^{\theta}$ of $\mathrm{AO}(s), \mathrm{BO}_{2}(g)$ and $A B \mathrm{O}_{3}(s)$ is $-635, x$ and $-1210 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. $\left.\mathrm{ABO}_{3}(s) \rightarrow \mathrm{AO}(s)+\mathrm{BO}_{2}(g): \Delta_{r} H^{\Theta}=175 \mathrm{~kJ} \mathrm{~mol}^{-1}\right)$. What is the value of $x$ (in $\mathrm{kJ} \mathrm{mol}^{-1}$ )?

The standard enthalpy of combustion of C (graphite). $\mathrm{H}_2(g)$ and $\mathrm{CH}_3 \mathrm{OH}(l)$ respectively are $-393,-286$ and $-726 \mathrm{~kJ} \mathrm{~mol}^{-1}$. What is the standard enthalpy of formation of methanol?

At 61 K , one mole of an ideal gas of 1.0 L volume expands isothermally and reversibly to a final volume of 10.0 L . What is the work done in the expansion?

The standard enthalpy of formation $\left(\Delta_f H^{\varphi}\right)$ of ammonia is $-46.2 \mathrm{~kJ} \mathrm{~mol}^{-1}$, What is the $\Delta_{,} H^{\ominus}$ of the following reaction? $$ \mathrm{N}_2(g)+3 \mathrm{H}_2(g) \longrightarrow 2 \mathrm{NH}_3(g) $$