An equilibrium mixture of gases in a rigid, sealed container at constant temperature is described by the reaction
N2(g)+3H2(g)⇌2NH3(g).
Which of the following changes would alter neither the value of the equilibrium constant Kc nor the position of equilibrium?
a) Compressing the mixture to one-half of its original volume
b) Injecting additional N2(g) into the vessel
c) Introducing a finely divided iron catalyst into the mixture
d) Raising the temperature of the container by 25∘C