For the gas-phase equilibrium
R(g) ⇌ P(g)
three sealed 1.0 L containers at the same temperature contain the following particle counts:
• Diagram A: 3 R and 15 P
• Diagram B: 8 R and 12 P
• Diagram C: 15 R and 3 P
If the equilibrium constant Kc for the reaction is 0.20, indicate which diagram (A, B, or C) most closely represents a mixture at equilibrium.