Which of the following is not a unit of the equilibrium constant Kp? (where, Δx = number of moles of products number of moles of reactants) ?
A. (atm)Δx, when Δx is negative
B. (atm)Δx, when Δx is positive
C. Dimensionless, when Δx = 0
D. (atm)Δx2, when Δx > 0