Question $2(12$ marks$)$

Vapor flow rate $(kmo\frac{l}{h})$ for each simple distillation task separating a four$-$component mixture are give as follows:

a$)$ Determine all possible combined distillation sequences.

b$)$ Determine the best distillation sequence.

$\backslash$table$[[$Task no$.,$Task,Vapor load$],[1,\frac{A}{B}CD,100],[2,A\frac{B}{C}D,120],[3,AB\frac{C}{D},240],[4,\frac{B}{C}D,90],[5,B\frac{C}{D},130],[6,\frac{A}{B}C,140],[7,A\frac{B}{C},220],[8,\frac{C}{D},100],[9,\frac{B}{C},80],[10,\frac{A}{B},]]$