Section $2\mathrm{.}2$

$2\mathrm{.}5$ Which of the following $K-$value expressions, if any, is rigorous? For those expressions that are not rigorous, ci assumptions involved.

$($a$)K_i\frac{?}{b}=ar\frac{({)}_{iL}}{\frac{?}{?}}$bar $({)}_{iV}$

$($b$)K_i=\frac{{}_{iL}}{{}_{iL}}$

$($c$)K_i={}_{iL}$

$($d$)K_i={}_{iL}\frac{{}_{iL}}{\frac{?}{?}}$bar $({)}_{iV}$

$($e$)K_i=\frac{P_i^s}{P}$

$($f$)K_i={}_{iL}\frac{{}_{iL}}{{}_{iv}}{}_{iv}$

$($g$)K_i={}_{iL}\frac{P_i^s}{P}$

$2\mathrm{.}6$ Experimental measurements of Vaughan and Collins $[$In Chem., $34,885(1942)]$ for the propane$-$isopentane system at