The enthalpy of formation of ammonia is $-46.0 \ kJ \ mol^{-1}$. The enthalpy change for the reaction $2NH_{3(g)} \rightarrow N_{2(g)} + 3H_{2(g)}$ is ............... $kJ \ mol^{-1}$.

If the $\Delta H_{fusion}$ of a substance is $'x'$ and $\Delta H_{vap}$ is $'y'$,then $\Delta H_{sublimation}$ will be:

The reaction $CH_{4(g)} + Cl_{2(g)} \to CH_3Cl_{(g)} + HCl_{(g)}$ has $\Delta H = -25 \, kcal$. Given bond energies $BE(C-H) = 84 \, kcal$,$BE(H-Cl) = 103 \, kcal$,$BE(C-Cl) = x$,and $BE(Cl-Cl) = y$. If $\frac{x}{y} = \frac{9}{5}$,then find the value of $y$. (in $, kcal$)

Comment on the thermodynamic stability of $NO_{(g)}$,given:
$\frac{1}{2} N_{2(g)} + \frac{1}{2} O_{2(g)} \rightarrow NO_{(g)}; \Delta_r H^{\ominus} = 90 \, kJ \, mol^{-1}$
$NO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow NO_{2(g)}; \Delta_r H^{\ominus} = -74 \, kJ \, mol^{-1}$

The correct order of $\Delta_{f} H^{\circ}$ values of Diamond $(I)$, Graphite $(II)$, and Fullerene $(III)$ is:

If $(i)$ $C + O_2 \to CO_2$,$(ii)$ $C + 1/2 O_2 \to CO$,$(iii)$ $CO + 1/2 O_2 \to CO_2$,the heats of reaction are $Q$,$-12$,and $-10$ respectively. Then $Q =$ ?