Answer
$K_c = \frac{[CO][H_2]^3}{[CH_4][H_2O]}$
(b) $K_c = \frac{[ClF_3]^2}{[F_2]^3[Cl_2]}$
(c) $K_c = \frac{[HF]^2}{[H_2][F_2]}$
Work Step by Step
(a)
The balancing coefficient of the hydrogen gas $(H_2(g))$ is "3", so that will be the exponent of its concentration.
$K_c = \frac{[Products]}{[Reactants]} = \frac{[CO][H_2]^3}{[CH_4][H_2O]}$
The balancing coefficient of the $F_2(g)$ is "3", so that will be the exponent of its concentration.
The balancing coefficient of the $ClF_3(g)$ is "2", so that will be the exponent of its concentration.
(b) $K_c = \frac{[Products]}{[Reactants]} = \frac{[ClF_3]^2}{[F_2]^3[Cl_2]}$
The balancing coefficient of the $HF(g)$ is "2", so that will be the exponent of its concentration.
(c) $K_c = \frac{[Products]}{[Reactants]} = \frac{[HF]^2}{[H_2][F_2]}$
