What stress would shift the equilibrium position of the following system to the left?

N2O3 (g) ⇌ NO (g) + NO2 (g); ΔH is negative

Decreasing the concentration of N2O3

Heating the system

Adding a catalyst

Increasing the concentration of NO

Heating the system

Explanation:

According to the principle of Le Chatelier, for a system at equilibrium, a specific disturbance would make the equilibrium shift toward the direction which minimizes such a disturbance.

Since we wish to shift the equilibrium to the left, this means we wish to increase the concentration of products, as an excess in their concentration would make the products react and produce more reactants in order to lower the excess concentration of products.

Since heat is also a product, an increase in heat would shift the equilibrium toward the left, as this would consume the excess of heat by producing the reactants.