A gas mixture with 4.50 mol of Ar, x moles of Ne, and y moles of Xe is prepared at a pressure of 1 bar and a temperature of 298 K. The total number of moles in the mixture is five times that of Ar. Write an expression for ΔG _mixing in terms of x. At what value of x does the magnitude of ΔG _mixing have its minimum value? Calculate ΔG _mixing for this value of x.