Question

The vapour pressure of a solvent decreases by
10 mm. of Hg when a non volatile solute was made be the mole fraction
of the solvent if the decrease in vapour pressure is
to be 20 mm of Hg :-
(1) 0.2 (2) 0.4 (3) 0.6 (4) 0.8
Thonour pressure of a solution of 5.0 of non

Answer 1

Answer:

We know,

P

o

−P

S

=P

o

× Mole fraction of solute

10=P

o

×0.2 ------ 1

20=P

o

×χ

2

------2

Solving equation 1 and 2 we get,

∴χ

2

=0.4

⇒χ

1

(solvent)=1−0.4=0.6

Option B is correct.