Class 12 Chemistry
Chapter 2 - Solutions
(Magical Series) Very Important Questions Set 5
Q.1. 18 g of glucose, C6H12O6 (Molar mass = 180 g mol–1) is dissolved in 1 kg of water in a sauce pan. At what temperature will this solution boil? (Kb for water = 0.52 K kg mol–1, boiling point of pure water = 373.15 K)
[Ans: 373.202 K]
Q.2. An aqueous solution of sodium chloride freezes below 273 K. Explain the lowering in freezing point of water with the help of a suitable diagram.
Q.3. Define the terms osmosis and osmotic pressure. Is the osmotic pressure of a solution a colligative property? Explain.
Q.4. List any four factors on which the colligative properties of a solution depend.
Q.5. Outer hard shells of two eggs are removed. One of the eggs is placed in pure water and the other is placed in saturated solution of sodium chloride. What will be observed and why?
Q.6. Find the boiling point of a solution containing 0.520 g of glucose (C6H12O6) dissolved in 80.2 g of water. [Given: Kb for water = 0.52 K/m]
[Ans: 373.019 K]
Q.7. A 10% solution (by mass) of sucrose in water has freezing point of 269.15 K. Calculate the freezing point of 10% glucose in water, if freezing point of pure water is 273.15 K. (Given: Molar mass of sucrose = 342 g mol–1, molar mass of glucose = 180 g mol–1).
[Ans: 265.55 K]
Q.8. 30 g of urea (M = 60 g mol–1] is dissolved in 846 g of water. Calculate the vapour pressure of water for this solution if vapour pressure of pure water at 298 K is 23.8 mm Hg.
[Ans: 23.5 mm Hg]
Q.9. Calculate the freezing point of the solution when 31 g of ethylene glycol (C2H6O2) is dissolved in 500 g of water. (Kf for water = 1.86 K kg mol–1).
[Ans: 270.52 K]
Q.10. A solution containing 15 g urea (molar mass = 60 g mol–1) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass= 180 g mol−1) in water. Calculate the mass of glucose present in one litre of its solution.
[Ans: 45 g]
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