A non-key component may be distributed if
(a) Close to that of one key
(b) The Specified separation is sloppy
(c) Intermediate between keys
(d) Intermediate one key
I had been asked this question by my college director while I was bunking the class.
This intriguing question comes from Reflux Stage Relationships topic in division Column Process Design, Optimization and Shortcut Calculations of Distillation Design