What is relation between relative lowering of vapour pressure and molality of solution?

ILLUSTRATION

(1) calculate weight of urea which must be dissolved in 400 gm of water so that final has V.P. 2% than V.P. of pure water?

(2) 10 gm of a solute is dissolved in 80 

gm of acetone V.P. of solution is 271 mm Hg. If V.P. of pure acetone is 283 mm of Hg. calculate molar mass of solute.

(3) Vapour pressure of a solution containing 6 gm of non volatile solute in 180 gm of water is 20 torr/mmHg. If 1 mole of water is further added in to the V.P. increases by 0.02 torr. calculate the V.P. of pure water and molecular wt of the non volatile solute.

Related Questions;

(1) An aqueous solution has 5% urea and 10% glucose by weight. what will be the freezing point of this solution ? ( Kf = 1.86 K Kg per mole)

(2) Acetic acid dimerised to an extent of 30% in benzene . The observed molecular mass (in gm) is...

(3) How much ice will separate if a solution containing 25 g of ethylene glycol [C2H4(OH) 2] in 100g of water is cooled to 10°C? Kf(H2O) = 1.86 (25.05 g)

(4) The dielectric con stant of H2O is 80. The electrostatic force of attraction between Na+ and Cl–will be.

(5) The van't Hoff's factor for 0.1 M Ba(NO3)2 solution is 2.74. the degree of dissociation is.