If the percentage dissociation of N2O4 is 50, the ratio of Kp and Peq for N2O4 ⇌2 NO2  becomes equal to

Total moles at equilibrium = 0.5 +1 = 1.5Partial pressure of N2O4 = χN2O4×Peq=0.5×Peq1.5=Peq3Partial pressure of NO2 = χNO2×Peq = 1×Peq1.5=2Peq3 Kp = PNO22PN2O4=4Peq29Peq3=4Peq3KpPeq=43