Chemistry : Part I for Class XII
Solutions - 02

Instructions

1. All questions are compulsary.
2. Please give the explanation for the answer where applicable.
3. To view the answer, click on the Answer link alongside the Question.
You can view the answer when the link becomesGreen Red. on completion of allocated time.


Q.1) Vapour pressure of pure water is 40mm. If a non-volatile solute is added to it, vapour pressure falls by 4 mm. Calculate molality of solution. (3 Marks) 

Q.2) A solution is prepared by dissolving 30g of non-volatile non-electrolyte solute in 90g water. The vapour pressure of solution was 2.8 K Pa at 298K. When 18g of water was further added to it, the vapour pressure became 2.9 k Pa at 298K. Calculate molar mass of solute. (3 Marks) 

Q.3) Vapour pressure of dilute solution of glucose is 750 mm of Hg at 373K. Calculate the mole fraction of solute. (2 Marks) 

Q.4) The vapour pressure of water at 296K is 19.8 mm of Hg, 0.1 mol of glucose is dissolved in 178.2g of water. Calculate the vapour pressure of resultant solution.  (3 Marks) 

Q.5) An aqueous solution freezes at –0.186°C.  Kf = 1.86°, Kb = 0.512. Find elevation in boiling point. (2 Marks) 

Q.6) Density of 1 M solution of glucose 1.18g/cm3. Kf for H2O is 1.86 Km–1. Find freezing point of solution.  (2 Marks) 

Q.7) Vapour pressure of two liquid A and B are 120 and 180mm Hg at a given temperature. If 2 mole of A and 3 mole of B are mixed to form an ideal solution, calculate the vapour pressure of solution at the same temperature. (2 Marks) 

Q.8) Why is the vapour pressure of a liquid remains constant at constant temperature? (1 Marks) 

Q.9) Define Azeotropes? (1 Marks) 

Q.10) Which substance is usually added into water in the car radiator to act as antifreeze? (1 Marks)