One of the following equilibria is not affected by change in volume of the flask :

Question

( A ) $N_2(g) +O_2(g) \rightleftharpoons 2NO (g)$
( B ) $N_2 (g) + 3H_2 (g) \rightleftharpoons 2NH_3 (g)$
( C ) $PCl_5 (g) \leftrightharpoons PCl_3 (g) +Cl_2 (g)$
( D ) $SO_2Cl_2 (g) \leftrightharpoons SO_2(g) +Cl_2(g)$