a$)$ Given the data below, calculate the vapor mole fraction of B above an A$-$B melt at

$1350$ K$.(10$ points$)$

At $1350K$ :

$x_B=0\mathrm{.}5,a_B=0\mathrm{.}200,a_A=0\mathrm{.}600,p_B={10}^{-6}$atm.,$p_A=2{10}^{-6}$atm.

b$)$ Would it be possible to vapor refine the A$-$B melt under conditions given

above? $(10$ points$)$