GKFix MCQ Question

What is the correct expression for Kp for the reaction Ni(s) + 4CO(g) ⇌ Ni(CO)₄(g)?

• A. Kp = pNi(CO)₄ × pNi / (pCO)⁴
• B. Kp = pNi × (pCO)⁴ / pNi(CO)₄
• C. Kp = pNi(CO)₄ / (pCO)⁴
• D. Kp = (pCO)⁴ / pNi(CO)₄