Final answer:
The correct reaction that fits the given equilibrium constant K = [A] / [B][C]² is option C: B (g) + C (g) ⇌ A (g), because the equilibrium constant expression matches the form of the given K.
Step-by-step explanation:
To determine which reaction fits the given equilibrium constant (K = [A] / [B][C]²), we can evaluate the provided options to see which reaction's equilibrium expression matches the form of the given K.
- A (g) + B (g) ⇌ C (g): This would give an equilibrium constant expression K = [C] / [A][B], which is not of the same form as the given K.
- A (g) ⇌ B (g) + 2 C (g): The correct equilibrium expression here would be K = [B][C]² / [A], which is the reciprocal of the given K.
- B (g) + C (g) ⇌ A (g): The equilibrium constant expression K = [A] / [B][C] matches exactly with the given K. So, option C is correct.
- B (a) + 2 C (a) ⇌ A (g): This would result in an expression K = [A] / [B][C]², considering (a) stands for aqueous solution, but due to the typo 'a' instead of '(aq)', it introduces confusion about the states of matter, and the standard form of K includes only gases and aqueous solutions, not solids.
Therefore, we can conclude that option C (B (g) + C (g) ⇌ A (g)) is the correct reaction that fits the given equilibrium constant K provided in the question.