Class 12 Chemistry

Chapter 2 - Solutions

(Magical Series) Very Important Questions Set 4

 

Q.1.     What are isotonic solutions?

Q.2.     Define Molal elevation constant (Boiling point elevation constant), K_b.

Q.3.     How is the vapour pressure of a solvent affected when a non-volatile solute is dissolved in it?

Q.4.     Define Osmotic pressure.

Q.5.     Calculate the freezing point of a solution containing 60 g of glucose (molar mass = 180 g Mol^–1) in 250 g of Water. (K_f of water = 1.86 K kg mol^–1)                 

[Ans: 270.52 K]

Q.6.     Give reasons for the following:

(a) Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.

(b) Elevation of boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.

Q.7.     (i) Out of 1 M glucose and 2 M glucose, which one has a higher boiling point and why?

(ii) What happens when the external pressure applied becomes more than the osmotic pressure of solution?

Q.8.     Blood cells are isotonic with 0.9% sodium chloride solution. What happens if we place blood cells in a solution containing

(i) 1.2% sodium chloride solution?

(ii) 0.4% sodium chloride solution?

Q.9.     Why does a solution containing non-volatile solute have higher boiling point than the pure solvent? Why is elevation of boiling point a colligative property?

Q.10.     Calculate the mass of compound (molar mass = 256 g mol^–1) to be dissolved in 75 g of benzene to lower its freezing point by 0.48 K. (K_f = 5.12 K kg mol^–1). 

[Ans: 1.8 g]

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