An ideal solution contains two volatile liquids `A(P^(@)=100` torr) and `B(P^(@)=200` torr). If mixture contain `1` mole of `A` and `4` mole of `B` then total vapour pressure of the distillate is :

Options

A. 150
B. 180
C. 188.88
D. 198.88

Answer

C

Explanation

`P_A^@x_A + P_B^@x_B rArr 100xx1/5 + 200 x4/5`
`rArr 180 ` torr
`y_A` (composition of vapour phase) `=(P_A^@x_A)/(P)`
`rArr 20/180 rArr 1/9 , :. Y_B = 8/9`
For condensation `y_A = x_A^1 , y_B = x_B^1` ,
`P_("total") = P_A^@x_A^1 + P_Bx_B^1` ,
`P_("total") = 1000 xx 1/9 + 8/9 xx 200 rArr 188.88` torr