Properties such as boiling point, freezing point and vapour pressure of a  Pure solvent change when solute molecules are added to get
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 autombiles A solution  M is prepared by mixing ethanol and water.  The mole Fraction of ethanol in the mixture is 0.9 
Given the freezing point depression constant of water  $({{\mathrm{K}}_{{\mathrm{f}}^{ }}}^{\mathrm{water}}=1.86\mathrm{K}{\mathrm{kgmol}}^{-1})$
Freezing point depression constant of ethanol = ${{\mathrm{K}}_{{\mathrm{f}}^{ }}}^{\mathrm{ethanol}}=2.0\mathrm{K}{\mathrm{Kgmol}}^{-1}$
Boiling point elevation constant of water=  ${{\mathrm{K}}_{\mathrm{b}}}^{\mathrm{water}}=0.52\mathrm{K}{\mathrm{Kgmol}}^{-1}$
Boiling point elevation  constant ethanol $={{\mathrm{K}}_{\mathrm{b}}}^{\mathrm{ethanol}}=1.2{\mathrm{KKgmol}}^{-1}$
Standard freezing point of water=273K
Standard freezing point of ethanol = 155.7 K
Standard boiling point  of water= 373K
Standard boiling point of ethanol= 351.5 K
Vapour pressure of pure water= 32.8 mm Hg
Vapour pressure of pure ethanol= 40 mm Hg
Molecular weight of water=  $18{\mathrm{gmol}}^{-1}$
Molecular weight of ethanol= $46 \mathrm{g} {\mathrm{mol}}^{-1}$
In answering the following questions consider the solution to be ideal dilute solutions and Solutes to be non-volatile and non-dissociative