When separating a mixture of propane, butane, pentane, hexane, and heptane we desire a $90\%$ recovery of butane in the distillate and a $90\%$ recovery of hexane in the bottoms. Circle $($mark$)$ the appropriate term for each component:

$7.)$ propane: $($a$)$ light key, $($b$)$ heavy key, $($c$)$ light non$-$key, $($d$)$ heavy non$-$key, $($e$)$ other non$-$key

$8.)$ butane: $($a$)$ light key, $($b$)$ heavy key, $($c$)$ light non$-$key, $($d$)$ heavy non$-$key, $($e$)$ other non$-$key

$9.)$ pentane: $($a$)$ light key, $($b$)$ heavy key, $($c$)$ light non$-$key, $($d$)$ heavy non$-$key, $($e$)$ other non$-$key

$10.)$ hexane: $($a$)$ light key, $($b$)$ heavy key, $($c$)$ light non$-$key, $($d$)$ heavy non$-$key, $($e$)$ other non$-$key

$11.)$ heptane: $($a$)$ light key, $($b$)$ heavy key, $($c$)$ light non$-$key, $($d$)$ heavy non$-$key, $($e$)$ other non$-$key