Chapter 15, Problem 4SAQ

What is the correct expression for the equilibrium constant $(K_{eq})$ for the reaction between carbon and hydrogen gas to form methane?

$\text{C}(s)+{\text{2H}}_{\text{2}}(g)\rightleftharpoons {\text{CH}}_{\text{4}}(g)$

a. $K_{eq}=\frac{\left[{\text{CH}}_{\text{4}}\right]}{\left[{\text{H}}_2\right]}$

b. $K_{eq}=\frac{\left[{\text{CH}}_{\text{4}}\right]}{\left[\text{C}\right]\left[{\text{H}}_2\right]}$

c. $K_{eq}=\frac{\left[{\text{CH}}_{\text{4}}\right]}{\left[\text{C}\right]{\left[{\text{H}}_2\right]}^2}$

d. $K_{eq}=\frac{\left[{\text{CH}}_{\text{4}}\right]}{{\left[{\text{H}}_2\right]}^2}$