Lron reacts with atmospheric oxygen to form iron oxide or ferric oxide. look at the chemical equation for this reaction

if the concentration of products is decreased, the equilibrium will shift toward the products). add an inert gas (one that is not involved in the reaction) to the constant-volume reaction mixture: this will increase the total pressure of the system, but will have no effect on the equilibrium condition.

explanation:

the correct answer to this question is 2