Which reaction is not affected by change in pressure? (AFMC 2009) (a) (g) (g) (g) H I 2HI (b) (s) (g) (g) 2C O 2CO (c) (s) (g) (g) N 3H 2NH (d) (g) (g) (g) PCl PCl Cl

Here, Δn for the reaction in option (a) is 0 whereas for other option it is not equal to 0. Hence, change in pressure will not have any effect on the equilibrium of reaction in option (a).