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. Application 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 0.9. Given : Freezing point depression constant of water (K_(f)^("water"))="1.86 K kg mol"^(-1) Freezing point depression constant of ethanol (e_(f)^("ethanol"))="2.0 K kg mol"^(-1) Boiling point elevation constant of water (K_(b)^("water"))="0.52 K kg mol"^(-1) Boiling point elevation constant of ethanol (K_(b)^("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 pressusre 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 non-dissociative. The vapour pressure of the solution M is