At `25^(@)C`, the total pressure of an ideal solution obtained by mixing 3 mole of A and 2 mole of B, is 184 torr. What is the vapour pressure (in torr) of pure B at the same temperature (Vapour pressure of pure A at `25^(@)C` is 200 torr) ?

Options

A. 180
B. 160
C. 16
D. 100

Answer

B

Explanation

`x_(A)=(n_(A))/(n_(A)+n_(B))=(3)/(3+2)=(3)/(5)=0.6`
`x_(B)=0.4`
`p=p_(A)^(0)x_(A)+p_(B)^(0)x_(B)`
`184=200 xx 0.6 + p_(B)^(0) xx 0.4`
`184 = 120 + p_(B)^(0) xx 0.4`
`p_(B)^(0)=(64)/(0.4)=160` torr]