The reaction, $\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$ is exothermic and reversible. A mixture of N$_2$(g), H$_2$(g) and NH$_3$(g) is at equilibrium in a closed container. When a certain quantity of extra H$_2$(g) is introduced into the container, while keeping the volume constant, then which statement among the following is true?