JEE Advanced2017ChemistrySolutionsActual
Pure water freezes at 273   K and 1   bar pressure. The addition of 34 . 5   g of ethanol to 500   g of water changes the freezing point of the solution. Use the freezing point depression constant of water as 2   K   kg   mol - 1 . The figures shown below represent the plots of vapour pressure ( V . P . ) versus temperature ( T ). [Molecular weight of ethanol is 46 g 46   g 
Correct answer
3
Step-by-step solution
Ethanol should be considered yo be a non-volatile solute as per the given options. ΔT f = K f × m , ΔT f = 2 × 34 .5 46 × 0 .5 = 3 K , T f 0 = 273 K , T f = 270 K .