(Q3-11) A mixture contains 35 mol% isobutane, 25 mol% isopentane, and 40 mol% n-hexane is at 30 psia. This mixture is flashed at 582.74R where 40 mol% of the feed is evaporated and at these conditions Kic4 = 3.1718, Kics = 1.051, and Knco = 0.3169. The fraction of isobutane in the feed recovered in the vapor phase is 0.679 0.629 O 0.589 None of the given answers