Question

The vapour pressure of a certain pure liquid $A$ at 100 K is 40 m bar. When a solution of $B$ is prepared in $A$ at the same temperature, the vapour pressure is found to be 32 m bar. The mole fraction of $A$ in the solution is:

• A. 0.5
• B. 0.2
• C. 0.1
• D. 0.8

Answer 1

The correct option is D 0.8

ANS; D

the vapour pressure of A = 40 m bar

after prepared of solution of B in A vapour pressure of solution =32m bar

mole prection of A =$\frac{v.pr.ofA.in-solution}{v.pr.ofA.inpure}$

= $\frac{32}{40}$ = 0.8