Answer:
Kp = P (N₂) . P³ (H₂)  /  P² (NH₃)
Explanation:
The reaction for the decomposition of ammonia is given by;
2NH₃ (g) ⇌ N₂ (g) + 3H₂ (g)
The pressure equilibrium constant gives the ratio of the pressure of the product over reactants for a reaction that is at equilibrium.
The pressures of the species are raised to the powers of their respective coefficients.
In this reaction;
Products = Â Nâ‚‚ (g) + 3Hâ‚‚ (g)
Reactant = 2 NH₃ (g)
The pressure equilibrium constant (Kp) is given as;
Kp = P (N₂) . P³ (H₂)  /  P² (NH₃)