Determine the sequence of distillation columns required to separate a mixture of six components A
F into individual species. The molar flows are 40, 5, 10, 25, 30, and 45 kmol/h, respectively. The order of volatilities is ABCDEF from higher to lower. The relative volatilities are as follows:

αAB 51:05; αBC 52:5; αCD 51:05; αDE 51:8; αEF 52:5

αAB;extractive 51:7; αCD;extractive 51:8