A plant has a batch of 100 kmol of a liquid mixture containing 20 mol% benzene and 80 mol% chlorobenzene. It is desired to rectify this mixture at 1 atm to obtain bottoms containing only 0.1 mol% benzene. The relative volatility may be assumed constant at 4.13. There are available a suitable still to vaporize the feed, a column containing the equivalent of four theoretical plates, a total condenser, and a reflux drum to collect the condensed overhead. The run is to be made at total reflux. While the steady state is being approached, a finite amount of distillate is held in a reflux trap. When the steady state is reached, the bottoms contain 0.1 mol% benzene. With this apparatus, what yield of bottoms can be obtained? The liquid holdup in the column is negligible compared to that in the still and in the reflux drum.