What is equilibrium expression for the reaction $ P_4 + 5O_2 \rightleftharpoons P_4O_{10} $
$ P_{4(S)}+ 5O_{2(g)} \rightleftharpoons P_4O_{10(s)} $ $ K_C = { [P_4 O_{10} \over [P_{4(s) ] [ O_{2(g)] ^ 5 $ we know that concentration of a solid component is always taken as a unity $ \therefore Kc = { 1 \over [ O_2 ] ^ 5 $