Chemistry - Thermochemistry Question with Solution | TestHub

$\left(\frac{1}{2}{\mathrm{N}}_2+{\mathrm{O}}_2\to {\mathrm{NO}}_2\Delta \mathrm{H}=32\mathrm{kJ}\right)\dots$ (1)

${\mathrm{N}}_2+2{\mathrm{O}}_2⟶{\mathrm{N}}_2{\mathrm{O}}_4\Delta \mathrm{H}=10\mathrm{kJ}$ ........(2)

(eq ... (1)) ⟶ reverse & multiply with 2 & add with reaction $\therefore 2{\mathrm{NO}}_2(\mathrm{g})⟶{\mathrm{N}}_2{\mathrm{O}}_4(\mathrm{g})\Delta \mathrm{H}=(10-64)\mathrm{kJ}$

$\Rightarrow \Delta \mathrm{H}=2\left({ϵ}_{\mathrm{N}-\mathrm{O}}\right)-\left[2\left({ϵ}_{\mathrm{N}=\mathrm{O}}\right)+{ϵ}_{\mathrm{N}-\mathrm{N}}\right]-54=-{ϵ}_{\mathrm{N}-\mathrm{N}}$

${ϵ}_{\mathrm{N}-\mathrm{N}}=54\mathrm{kJ}/$ mole (C) option