The reaction 2A + 4B↔C + 3D is carried out in the liquid phase, in a closed-system reactor at T + 400 K and P + 1 bar. At these conditions, the equilibrium constant is K₄₀₀ = 12.5, and the reaction mixture is an ideal solution.

A. If the reactor initially contains 5 moles each of A and B, what are the contents of the reactor at equilibrium? 

B. If the reactor initially contains one mole each of A, B, C, and D, what are the contents of the reactor at equilibrium? 

C. If the reactor initially contains two moles of A and two moles of C, what are the contents of the reactor at equilibrium?