Practice Questions Answers 2 => on chapter 2 (SOLUTIONS)

These are "Practice Questions Answers 2 => on chapter 2 (SOLUTIONS)" for 12th class CBSE Board Examinations.

Q1. Out of 1M and 1m aqueous solution which is more concentrated?

Ans. 1M as density of water is 1gm/ML.

Q2. Q2. Henry law constant for two gases are 21.5 and 49.5 atm ,which gas is more soluble . 

Ans. K_H is inversely proportional to solubility.

Q.3. Define azeotrope , give an example of maximum boiling azeotrope.

Ans. The mixture of liquids at particular composition which has constant boiling point which behaves like a pure liquid and cannot be separated by simple distillation. 

=>Maximum Boiling Azeotrope (which shows –ve deviations) ex. acetone and chloroform.

Q.4. How many grams of KCl should be added to 1kg of water to lower its freezing point to -8.0⁰C (kf = 1.86 K kg /mol).

Ans. Ans. Since KCl dissociate in water completely L=2 ; 

m = 8 / (2) x (1.86) 

    = 2.15mol/kg. 

Grams of KCl= (2.15) x (74.5) 

= 160.2 g.

Q.5. What type of liquids form ideal solutions? 

Ans. Liquids having similar structures and polarities.  

Q6.Why does chemist prefer to refer concentration of solution in terms of molality? 

(Or)

Which of the two molality and molarity is better to express concentration of solution? Why? 

Ans. Molality does not change with temperature where as molarity changes with temperature because volume changes with temperature. Therefore molality is better.  

Q7. What is van’tHoff factor for KCl in aqueous solution? i = 2 . 

Ans. i = 2.

Q8. What happens when blood cells are placed in pure water? 

Ans. Due to osmosis water enters the blood cells through the cell wall, as a result it swells and may even burst. 

Q9. Two liquids say X and Y boil at 380 K and 400 K respectively. Which of them is more volatile? Why? 

Ans. Liquid – X because lower the boiling point more will be volatile (evaporation).

Q.10.What is the effect of rise in temperature on solubility of gases? Ans.Dissolution of gas is exothermic process. Hence according to Le Chatelier‘s principle, the solubility of gas should decrease with rise in temperature