The gas phase reaction $2{\mathrm{NO}}_{2( \mathrm{g})}\to {\mathrm{N}}_2{\mathrm{O}}_4$ (g) is an exothermic reaction. The decomposition of ${\mathrm{N}}_2{\mathrm{O}}_4$, in equilibrium mixture of${\mathrm{NO}}_2( \mathrm{g}$) and ${\mathrm{N}}_2{\mathrm{O}}_4( \mathrm{g})$, can be increase by

The reaction at equilibrium is:

$N_2{O}_4\rightleftharpoons 2N{O}_2$

Le Chatelier's principle states that when pressure is applied to a gas reaction, the equilibrium position is shifted to the side with less molecules.

As a result, it will migrate backward, which causes $N{O}_2$ to become $N_2{O}_4$.

When an inert gas is added at constant pressure, the volume increases and the equilibrium shifts in favour of more molecules, leading to breakdown.

$N_2{O}_4$ decomposition is endothermic. As a result, as the temperature rises, the reaction will advance.

Therefore, the correct option is (D).