Properties such as boiling point, freezing point and vapor pressure of a pure solvent Change when solute molecules are added to get a homogeneous solution. These are called colligative properties. Applications of Colligative properties are very useful in day-to-day life one of its examples is the use of ethylene glycol and water mixture as anti- freezing liquid in the radiator of automobiles. A solution M is prepared by mixing 
ethanol and water. The mole fraction of ethanol in the mixture is 0.8.
Given: 
Freezing point depression constant of water $\left({\mathrm{K}}_{\mathrm{f}}\right)=1.86 \mathrm{kg} {\mathrm{mol}}^{-1}$
Freezing point depression constant of ethanol $\left({\mathrm{K}}_{\mathrm{f}}\right)=2\mathrm{kg}{\mathrm{mol}}^{-1}$ 
Boiling point elevation constant of water $\left({\mathrm{K}}_{\mathrm{b}}\right)=0.52\mathrm{kg}{\mathrm{mol}}^{-1}$
Boiling point elevation constant of ethanol $\left({\mathrm{K}}_{\mathrm{b}}\right)=1.2\mathrm{kg}{\mathrm{mol}}^{-1}$
Standard freezing point of water =273 K
Standard freezing point of ethanol =155.7 K
Standard  boiling point of water =373 K
Standard  boiling point of  ethanol =351.5 K
Vapour pressure of water = 32.8 mm Hg
Vapour pressure of ethanol  =40 mm Hg
Molecular weight of water $=18 \mathrm{g} {\mathrm{mol}}^{-1}$
Molecular weight of ethanol $=46\mathrm{g} {\mathrm{mol}}^{-1}$
In answering the following questions, consider the solutions to be ideal dilute solutions and solutes to be non-volatile and non-dissociative.