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-today 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 0.9. Given: Freezing point depression constant of water ( K f text water )=1.86 K kg mol -1 Freezing point depression constant of ethanol ( K f text ethanol )=2.0 K kg mol -1 Boiling point elevation constant of water ( K b textwater )=0.52 K kg mol -1 Boiling point elevation constant of ethanol ( K b text ethanol )=1.2 K kg 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 pure water =32.8 mm Hg Vapour pressure of pure ethanol =40 mm Hg Molecular weight of water =18 g mol -1 Molecular weight of ethanol =46 g mol -1 In answering the following questions, consider the solutions to be ideal dilute solutions and solutes to be non-volatile and nondissociative. The vapour pressure of the solution M is