Consider the gas phase equilibrium: 2H2 (g) + O2 (g) ⇌ 2H2O (g) + heat. Of oxygen is added to the system. Equilibrium shifts towards ? g

Equilibrium position shifts right.

Explanation:

According to Le Châtelier's principle, when a chemical system at equilibrium is distributed by a change in conditions, the equilibrium position will shift in a direction that tends to counteract the change.

So, when the concentration of reactant increases, the equilibrium will counteract the change by increasing the concentration of the products, hence shifting right to increase the concentration of water.