Given,

$$ \mathrm{H}_2(g)+\frac{1}{2} \mathrm{O}_2(g) \longrightarrow \mathrm{H}_2 \mathrm{O}(l) ; \Delta H=-285 \mathrm{~kJ} $$

$$ \begin{aligned} & \mathrm{N}_2 \mathrm{O}_5(g)+\mathrm{H}_2 \mathrm{O}(l) \longrightarrow 2 \mathrm{HNO}_3(l) ; \Delta H=-76.6 \mathrm{~kJ} \\ & \mathrm{~N}_2(g)+3 \mathrm{O}_2(g)+\mathrm{H}_2(g) \longrightarrow 2 \mathrm{HNO}_3(l) ; \\ & \Delta H=-348.2 \mathrm{~kJ} \end{aligned} $$

Calculate the $\Delta \mathrm{H}$ of $2 \mathrm{~N}_2(\mathrm{~g})+5 \mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{~N}_2 \mathrm{O}_5(\mathrm{~g})$.

The change in enthalpy $[\Delta H]$ in $\mathrm{kJ} \mathrm{mol}^{-1}$ for the reaction, $\mathrm{Mg}+2 \mathrm{~F} \longrightarrow \mathrm{MgF}_2$ is

Given, electron affinity of $\mathrm{F}=328 \mathrm{~kJ} \mathrm{~mol}^{-1}$,

IE ${ }_1$ of $\mathrm{Mg}=737 \mathrm{kJmol}^{-1}, \mathrm{IE}_2$ of $\mathrm{Mg}=1451 \mathrm{kJmol}^{-1}$

A certain mass of a gas was brought from state $A$ to $B$ by following three different paths, namely 1,2 and 3 , respectively. Which of the following relations is correct for the work done?

Among the following given substances, the one with zero $\Delta_f H^{\circ}$ is