Given are the following informations at 298 K.

$\begin{array}{l}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{N}}_2{\mathrm{O}}_4\left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{NO}}_2\left(\mathrm{g}\right)\\ {\mathrm{\Delta }}_{\mathrm{f}}{H}^{\circ }/\mathrm{kJ}{\mathrm{mol}}^{-1}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}9.16\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}33.18\\ {\mathrm{\Delta }}_{\mathrm{f}}{G}^{\circ }/\mathrm{kJ}{\mathrm{mol}}^{-1}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}97.54\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}51.31\end{array}$

The reaction is carried out in a closed vessel starting from ${\mathrm{N}}_2{\mathrm{O}}_4$.

If the reaction is started with 1 mo! of ${\mathrm{N}}_2{\mathrm{O}}_4$ and 0.5 mo! of ${\mathrm{N}}_2$ at the constant pressure condition, the degree of dissociation of ${\mathrm{N}}_2{\mathrm{O}}_4$ at equilibrium relative to that of the reaction started only with 1 mol of ${\mathrm{N}}_2{\mathrm{O}}_4$

The addition of inert gas at constant pressure causes the reaction to proceed towards larger number of gaseous species. The overall pressure will rise if an inert gas is injected to the equilibrium system at a constant volume. The ratio of the reactants' and products' moles to the capacity of the container, however, won't affect the concentration of the two. As a result, there won't be any changes to the equilibrium's position.