(a) When 2.56 g of sulphur was dissolved in 100 g of CS
2
, the freezing point lowered by 0.383 K.Calculate the formula of sulphur (S
x
)
(b) 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 [March 2016] [5]
16. (a) A 10% solution (by mass) of sucrose in water has a freezing point of 269.15K. Calculate the freezing point of 10% glucose in
water if the freezing point of pure water is 273.15K. (Molar mass of sucrose = 342 g mol
−
1
)(molar mass of glucose = 180 g mol
−
1
)
(b) Define the following terms:
(i) Molality (m) (ii) Abnormal molar mass
[OR]
(a) 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
(b) Write two difference between ideal solutions and non-ideal solutions [March 2017] [5]
17. 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
) [March 2018] [2]
18. Give reason 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) Aquatic animals are more comfortable in cold water than in warm water.
(c) Elevation of boiling point of 1M KCl solution is nearly double than that of 1M sugar solution.
[March 2018] [3]
19. (a) Aquatic species are more comfortable in cold water than warm water.
(b) At higher altitudes people suffer from anoxia resulting in inability to think.
[OR]
What type of azeotropic mixture will be formed by a solution of acetone and chloroform? Justify on the basis of strength of
intermolecular interactions that develop in the solution? [March 2019] [2]
20. At 300 K, 30 g of glucose present in a litre of its solution has an osmotic pressure of 4.95 bar. If the osmotic pressure of a glucose
solution is 1.52 bar at the same temperature, what would be its concentration?
[March 2019] [3]
21. 50 mL of an aqueous solution of glucose C
6
H
12
O
6
(molar mass – 180 g/mol) contains 6.022 x 10
22
molecules.
The concentration of the solution will be
(a) 0.1 M (b) 0.2 M (c) 1.0 M (d) 2.0 M [March 2020] [1]
22. Predict the state of the solute in the solution in the following situation
(i) When ‘I’ found to be more than one
(ii) When ‘I’ found to be less than one. [March 2020] [2]
23. An antifreeze solution is prepared by dissolving 31g of ethylene glycol (Molar mass 62 g/mol) in 600g of water. Calculate the
freezing point of the solution (K
f
of water = 1.86 Kkg/mol) [March 2020] [3]
24. When 1 mole of benzene is mixed with 1 mole of toluene The vapour will contain:
(Given : vapour of benzene = 12.8kPa and vapour pressure of toluene = 3.85 kPa).
a) equal amount of benzene and toluene as it forms an ideal solution
b) unequal amount of benzene and toluene as it forms a non ideal solution
c) higher percentage of benzene
d) higher percentage of toluene [Sample paper 2021] [1]
25. Assertion: Aquatic species are more comfortable in cold waters rather than in warm waters.
Reason: Different gases have different K
H
values at the same temperature
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
OR
Assertion: Nitric acid and water form maximum boiling azeotrope.
Reason: Azeotropes are binary mixtures having the same composition in liquid and vapour phase
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
[Sample paper 2021] [1]
26. A glucose solution which boils at 101.04
o
C at 1 atm. What will be relative lowering of vapour pressure of an aqueous solution of
urea which is equimolal to given glucose solution? (Given: K
b
for water is 0.52 K kg mol
-1
)
[Sample paper 2021] [2]
