A vessel contains N2O4  at certain temperature & 2 atm. If the degree of dissociation of N2O4  at equilibrium is 0.2, final pressure of system (in atm)?

N2O4⇌2NO2    1                     0       0.2               0.4  _   0.8              0.4     1 mole  −−−−  2 atm 1.2 mole  −−−−  ?              =1.21×2              =2.4atm