Answer
$K_{c} = \frac{[CS_{2}][H_{2}]^4}{[H_{2}S]^2[CH_{4}]}$
homogeneous
Work Step by Step
The expression for Kc is the concentration of products raised to their respective stoichiometric coefficients divided by the concentration of the reactants raised to their stoichiometric coefficients.
For the reaction:
CH4 + 2H2S CS2 + 4H2
we would have
$K_{c} = \frac{[CS_{2}][H_{2}]^4}{[H_{2}S]^2[CH_{4}]}$
Since all reactants are in the gas phase, the reaction is homogeneous (same phase)
