Ch 1 class 12

1. UNIVERSAL PUBLIC SCHOOL
SESSION (2015-16)
CLASS – XII Subject: Chemistry
Assignment 2(I) Topic - Solutions
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1. Two liquids A and B boil at 1450
C and 1900
C respectively. Which of them has a higher vapor pressure at
800
C ?
2. Give an example of solution containing a solid solute in a solid solvent.
3. Oil and water do not mix. Why ?
4. When and why is molality preferred over molarity in handling solutions in chemistry ?
5. What is an isotonic solution? Give example.
6. What would be the value of Vant Hoff factor for a dilute solution of K2SO4 in water ?
7. State Henry’s law. What is the significance of KH.
8. Two liquids A and B on mixing produce a warm solution. Which type of deviation is there and why?
9. (a) Define osmotic pressure. (b) Why is osmotic pressure of 1 M KCl higher than 1 M Urea solution.
10. (a) What do you understand by “Colligative properties” ? Give example. (b) Why osmotic pressure is
preferred over other colligative properties for the determination of molecular masses of
macromolecules?
11. What is the molar concentration of particles in human blood if the osmotic pressure is 7.2 atm at normal
body temperature of 37 o
C? [Ans:
12. What is reverse osmosis ?
13. Define the following: (i) Cryoscopic constant (ii) Ebullioscopic constant (iii) Azeotropes
14. 75.2 g of C6H5OH (phenol) is dissolved in solvent of Kf = 14. If the depression in freezing point is 7 K, then
find the % of phenol that dimerises.
15. CCl4 and water are immiscible whereas ethanol and water are miscible in all proportions. Correlate this
behavior with molecular structure of these compounds.
16. The molarity of a solution of sulphuric acid is 1.35 M. Calculate its molality (The density of the acid
solution is 1.02 g cm -3
)
17. (a) Why is the vapour pressure of a solution of glucose in water lower than that of water ?
(b) A 6.90 solution of KOH in water contains 30% by mass of KOH. Calculate the density of the KOH
Solution ? (Molar mass of KOH = 56 g mol -1
)
18. (a) What is vant Hoff factor? What is its significance?
(b) What is maximum boiling azeotrope? Give one example of each.
19. (a) State Raoult’s law for a solution of two volatile liquids. With the help of Raoult’s law show that total
vapour pressure of a binary liquid solution varies linearly with the mole fraction of a component.
20. Non ideal solution exhibit either positive or negative deviations from Raoult’s law. What are these
deviations and why are they caused? Explain with one example for each type.
21. Derive the relationship between the relative lowering of vapour pressure and mole fraction of the
volatile liquid.
22. (a) Show that the relative lowering of vapour pressure of a solvent is a colligative property. (b) Can we
separate water completely from HNO3 solution by vapourisation? Justify your answer.
23. Give reason :- (a) Aquatic species are more comfortable in cold water than in warm water. (b) Cold drinks
bottles are sealed under high pressure. (c) To avoid bends scuba divers use air diluted with helium.
24. When 1 mole of NaCl is added to 1 litre water the boiling point increases. When 1 mole of CH3OH is added
to 1 litre water the boiling point decreases. Give reason.