What is the equilibrium expression for:
fe3o4(s) + 4h2(g) <=> 3fe(s) + 4h2o(g)
kc =

a)[fe]3 [h2o]4 / [fe3o4] [h2]4
b)[fe3o4] [h2]4 / [fe]3 [h2o]4
c)[h2o]4 / [h2]4
d)[fe] [h2o] / [fe3o4] [h2]