1adding inert gas at equilibria at cons vol increases the the total pressure of the system but the pressure of the gases in equilibria remains the same ........and as by daltons law GASES BEHAVES INDIVIDUALLY no effect is done therefore adding inert gas at equilibria at constant volume conditions makes no effect on equilibria ..........
in case of constant pressure cond we have to reduce the presuure of gasses in equililibria to compensate the extra pressure by inert gas ....therfore pressure of the gases in equilibria get reduced therefore equilibria will shift in the direction where gaseous no of mole is high........
