What is the effect of a ten-fold increase in pressure on KP in the reaction at equilibrium $N_2\left(g\right)+ 3H_2\left(g\right) \rightleftharpoons 2N{H}_3\left(g\right)?$

Since KP only depends on temperature, as we are aware, the eqn constant won't change at all as pressure is increased.

Therefore, the correct answer is option (C) No change.