Final answer:
The correct equilibrium constant expression for the given reaction CO(g) + 2H₂(g) → CH₃OH(g) is K = [CH₃OH] / ([CO][H₂]²), which corresponds to option (b) in the question.
Step-by-step explanation:
The question asks for the equilibrium constant expression for the reversible reaction: CO(g) + 2H₂(g) → CH₃OH(g). According to the law of mass action, the equilibrium constant expression for a chemical reaction is the product of the molar concentrations of the products raised to the power of their stoichiometric coefficients, divided by the product of the molar concentrations of the reactants raised to the power of their stoichiometric coefficients.
In this case, the correct equilibrium constant expression, consistent with the stoichiometry of the balanced chemical equation, is K = [CH₃OH] / ([CO][H₂]²). This corresponds to option (b): [CH3OH]/[CO][H₂]².
Adjustments made to the system at equilibrium, such as changing concentrations or temperature, will affect the direction in which the equilibrium shifts, according to Le Chatelier's principle.