Question

Q.31. The relative lowering of vapour pressure of a dilute aqueous solution containing non-volatile solute is 0.0125. The molality of the solution is about
(1) 0.70
(2) 0.50
(3) 0.90
(4) 0.60

Answer 1

Dear student ,
as we know that from Raoult's law; $\frac{P0-Ps}{P0}=\frac{molality\times M}{1000}$
on putting the values
0.0125 =$\frac{molality\times 18}{1000}$
molality = 0.69 (0.7) m (option 1)
Regards