A mixture of Nitrogen and Hydrogen is at an initial pressure of 200atm. If 20% of the mixture reacts by the time equilibrium is reached, the equilibrium pressure of the mixture is

Initial pressure of mixture containing Nitrogen & Hydrogen = 200 atm;Percentage of the mixture reacted = 20%Thus decrease in pressure due to reactionPressure ∝ number of moles4 moles of reactants give 2 moles of products.Thus if the decrease in pressure of reactant is 40 atm then increase in pressure of product  ∴Equilibrium pressure = (160 + 20) atm                                      = 180 atm