Relation between Kp and KC is as folows KpKC(RT)∆n where, Kp= equilibrium constant when concentrations at equilibrium are expressed in atmospheric pressure. KC= equilibrium constant when concentrations at equilibrium are expressed in molarity. R= gas constant T= temperature ∆n= the changed in number of moles of gas molecules. [∆n= number of gaseous moles in product- number of gaseous moles in reactant] For reaction, N2(g)+3H2(g)⇌2NH3(g)+Heat Kp=KC(RT)2−(1+3) Kp=KC(RT)−2 Hence, correct answer is (c).