UNIT 1 SOLUTIONS

Multiple Choice Questions (MCas)

1. Which of the following is dependent on temperature?
a) Molarity b) Mole fraction c) Weight percentage d) Molality
2. Which of the following compounds can be used as antifreeze in automobile radiators?
a) Methyl alcohol b) Nitrophenol c) Glycol d) Ethylalcohol
3. The dissolution of gas is in a liquid is governed
a) Raoult's law b) Henry's law c) Dalton's law of pressure d) van't Hoff factor
4. The mole fraction of the solute in one molal aqueous solution is

a) 0.009 b)0.018 c) 0.027 d) 0.036

5. Out of following which one is not an example of a solution.
a) Air b) Brass c) amalgam d) benzene in water
6. If one mole of a substance is present in one kg of solvent, then

a) It shows molar concentration b) It shows molalconcentration

c) It shows normality d) It shows strength g/g

J 7. Statement I: On adding NaCl to water itsvapour pressure increases

Statement Il: Addition of non-volatile solute increases the vapour pressure.
a) Both statement I and Ilare correct
b) Both statementland statement Il are wrong
c) Statement Iis correct and statement Il is incorrect

d) Statement I is incorrect and statement Il is correct

8. PA and Pg are the vapour pressures of pure liquid components, Aand B, respectively of an ideal
binarysolution. If XA
represents the mole fraction of component A, the total pressure of the solution will be
a) Pa+ XA(Ps-Pa) b) Pa+ XA(PA-Pa) c) PatXa(P-Pa) d) PatXA(PA-Pa)
9.The vapour pressure of two liquids P andQ are 80 and 60 torr, respectively. The total vapour pressure of
solution obtained by mixing 3 mole of P and 2 mol of Qwould be
a) 72 torr b) 140 torr c) 68 torr d) 20 torr

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10. The mixture which shows positive deviation from Raoult's law is
a) ethanol + acetone b) benzene + toluene
d)chloroethane +
c)acetone + chloroform
bromoethane

11. The mixture that forms maximum boiling azeotrope is

a) heptane + octane b) water nitric acid
c) ethanol + water d)acetone + carbon disulphide.
12. Which of the following statements is correct regarding asolution of two components Aand Bexhibrting
positive deviation from ideal behaviour?
a) Intermolecular attractive forces between A-A and B-B are stronger than those between A-B.
b) AVmiH=0 at constant Tand P.
c) AVmiV=0 at constant Tand P.

d) Intermolecular attractive forces between A-A and B-B are equal to those between A-B.
13. Which of the following statements about the composition of the vapour over an ideal 1: 1 molar mixture
of benzene and toluene is correct? Assume that the temperature is constant at 25°C. (Given, vapour pressure
data at 25°C benzene 12.8 kP,, toluene = 3.85 kP,).
a) The vapour willcontain equal amounts of benzene and toluene.
b) Not enough information is given to make a prediction.

c) The vapour will contain ahigher percentage of benzene.

d) The vapour willcontain a higher percentage of toluene.
14. Asolution containing components Aand Bfollows Raoult's law.
a)A-B attraction force is greater than A-Aand B-B
b) A-B attraction force is less than A- Aand B- B
c) A-B attraction force remains same as A-Aand B-B
d) volume of solution is different from sum of volume of solute and solvent.

15. All form ideal solution except

a) C¢H; and CoHs,CH b) C,HG and CHl c) CoH;Cl and CçH,Br d) C,Hsl and C,H,OH
16. An ideal solution is formed when its components
a) have no volume change on mixing b) have no enthalpy change on mixing.
c) have both the above characteristics d) have high solubility.

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17.f molalityof the dilute solutlon Is doubled, the value of molal depression constant (K4) will be
a) halved b) tripled c) unchanged d)doubled.
18. During osmosis, flow of water through a semipermeable membrane is
a) from solution having lower concentration only
b) from solution having higher concentration only
)from both sides of semipermeable membrane with equal flow rates
d) from both sides of semipermeable membrane with unequal flow rates.
19. Pure water can be obtalned from sea water by
a) centrifugation b)plasmolysis c) reverse osmosis d) sedimentation
20. From the coligative propertles of solutlon, whlch one is the best method for the determination of
molecular weight of proteins and polymers?
a) Osmotic pressure b) Lowering in vapour pressure
c) Lowering in freezing point d) Elevation in boiling point
21. The relationship between osmotic pressure at 273 Kwhen 10 g glucose (pi), 10 g urea (p2), and 10 g
sucrose (p) are dissolved in 250 mL of water is.
a) P, > P,> P, b) P,> P> P; c) P,>P> P d) P;> P, > P.
22. Blood cells retain their normal shape in solution which are
a) hypotonic to blood b) isotonic to blood c) hypertonic to blood d) equinormal to
blood.

23. Of the following 0.10 maqueous solutlons, which one will exhibit the largest freeing point depression?
a) KCI b) CGH;,06 c) Al,(S0.). d) K,SO,

24. An aqueoussolution is 1.00 molal in KI. Which change willcausethe vapour pressure of the solution to
increase?

a) Addition of NaCI b) Addition of Na,SO, c) Addition of 1.00 molal KI d) Addition of

water

25.Which of the following salts has the same value of Van't Hoff factor (|) as that of K,[Fe(CN)J?

b) Al(NO,), c) Al,(S0a) d) NaCl

a) Na,SOA
solutlon of
26. At 25C the highest osmotic pressure Is exhibited by 0.1 M
a) Glucose b) urea c)CaCl, d) KCI
27. Which of the following aqueous solution has minimum freezing point?
a) 0.01 NaCI b) 0.005m C,H,OH c) 0.005m Mgl, d) 0.005m MgSO,
28. For 0.1 M solution, the colligative property will follow the order
a) NaCl > Na,SO> Na,PO4 b) NaCl< Na,SO< Na_PO4
c) NaCl >Na,sO, Na,PO4 d) NaCl < Na,SO, = Na,PO4

29. Statement I: If red blood cells were removed from the body and placed in pure water, pressure inside the
cells

Increases.

Statement Il :The concentration of salt content in the cells increases.

a) Both statements Iand Il are correct b) Both statements Iand llare incorrect
c) Statement I is correct and statement Il is incorrect d) Statement Iis incorrect and statement Il is
Correct

30. During depression of freezing point in asolution the following are in equilibrium
a) Liquid solvent, solid solvent b) Liquid solvent, solid solute
c) Liquid solute, solid solute d) Liquid solute, solid solvent

Fill in the blanks by choosing the appropriate word from those given in the brackets:
f Set-1

(Plasmolysis, mole fraction, Reverse osmosis, Solid, Liquid, Molarity)

1. Desalination of water is based on

2. The shrinking of a plant cell due to overflow of water is called

3. Hydrated salts are solutions of in solid.

4. 22 carat gold is an example of solid in solution.

is linear with slope equal to KH.

5. According to Henry's law the plot of equilibrium pressure versus

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 Set-2

(1, 0.9, lower, saturated solution, higher, unsaturated solution)

1. Red blood cells are isotonic with % NaCl solution

2.For non-electrolytes, the van't Hoff factor (i) is

3. Greater the value of Henry's constant of a gas is its solubility at the same partial pressure and
temperature.

4. An ionic compound dissolves in water if hydration energy is than lattice energy.

S. Asolution in which no more solute can be dissolved at the same temperature and pressure is called.
Set-3

(Nz, Isotonic, O,, hypotonic, Cellulose acetate, CO,)

in the blood.
1. In deep sea diving the disease called Bends is caused due to the dissolution of
2. At Altitude, concentration of in the blood is low. people feel weak and unable to think properly this
disease is

called anoxia.

3. Solutions having the same osmotic pressure are called

4. Asolution with lower osmotic pressure is called with respect to a more concentrated solution.
5.The semipermeable membrane generally used in the reverse osmosis is made up of

Set-4

(Azeotrope, solvent, association, solution, dissociation, solute)

1.Osmotic pressure is the minimum pressure that must be applied on the side to prevent the entry
of solvent

from solvent to solution.

2. Inosmosis, there is a net flow of solvent from to solution.

3. If van'tHoff factor is less than unity this shows that the solute undergoes in the solution

4. If van't Hoff factor is more than unity this shows that the solute undergoes in the solution.

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 called The
mole fraction is
5. The constant boiling mixture of two miscible liquids of a definite
semipermeable
membrane generally used in the reverse osmosis is made up of
Set-5

decrease, solute)
(Helium, solvent, Xenon, increase,
1. Molal elevation constant Kb depend upon the nature of the
particles dissolved in solution.
2.Colligative properties depend on the number of
in temperature.
3. Value of Henry's constant KH increases with
with increase of temperature.
4.As dissolution is an exothermic process the solubility should
5. See diverse for breathing inside see use a mixture of O2 and inert gas
Set-6

(Anoxia, Edema, More, Non-ideal, Osmotic pressure, less)

called
1. People taking a lot of salt develop swelling or puffiness of their tissues. This disease is
2. At the same temperature nitrogen gas is soluble in water than oxygen

3. The best colligative property to determine the molecular mass of polymers is

4. A solution showing negative deviations forman azeotrope with highest boiling point.

5. Less is the colligative property, is the Molecular mass.

Two marks questions:

1. What is saturated and unsaturated solution?What is the effect of temperature and pressure on the
solubility?

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2. Define the following terms i) Solution ii) Mole fraction i) Molarity iv) Molality

3. Which of the two molarity or molality, does vary with temperature? and how?

4. State Henry's law. Wrte its mathematical statement. What is the significance of Henry's Constant?

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5. Mention any two applications of Henry's law.

6.Why do gases always tend to be less soluble in liquids as the temperature increases? Explain.

7.What is Vapour pressure of liquids? Name a law which helps us to determine partial vapor pressure of a
volatile component in solution.
8.State Raoult's lavw as applied to a binary solution of Non-volatile solute in a volatile solvent.

9. What are ideal and non-ideal solutions?

10. Give an example of ldeal solution and non-ideal solutions.

 *wnat causes deviations from ideal behavior of solutions? Why do the vapour pressures of certain solutions
show negative or positive deviations from the Raoult's
law?

12. Derive the relation between molar mass of solute

and relative lowering vapour pressure.

13. What is azeotropic mixture? Give example.

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14. What are the different types of azeotropic mixtures? Explain with example.

15. What are colligative properties? Give examples.

16. Write the mathematical relation between molality and elevation in boiling point. What happens to boiling
point of water when salt is dissolved in it? Which one willhave greater boiling point: 0.1M NaCl, 0.1 MBaCl,?

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 molality and depression in freezing point. Why is sodium chloride
wie the mathematical relation between
used to clear snow on roads?

18. Write a note on osmotic pressure.

19.Define osmosis and semi permeable membrane.

20. Give reasons:

) Ctting onions taken from the fridge is more comtontable than Cutting
onions lying at room temperature I
would rather do that
: Aben fruits and vegetables that have dried are placea in
Water they slowlyswell and return to the original
form

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Three mark questions:
1. Define the following terms i) Mass percentage ii) volume percentage ii) Parts per million (ppm).

2. Give any three differences between ideal and non-ideal solutions.

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 3. Give any three differences between solutions showing positive and negative deviation from ideal
behaviour.

4. Define the term molalelevation constant and Molal depression constant. Give their Sl unit.

5. What is an isotonic, hypertonic and hypotonic solution?

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6. What is abnormal molar mass? Define Van't- Hoff's factor. What would be the value of Van't Hoff factor for a
dilute solution of K,SO, in water if it undergoes complete dissociation?

7. With the help of vapour pressure- temperature diagram, explain the depression of freezing point of a
solution of a non-volatile solute in a volatile solvent. How would you determine the molar masses of solute using
the above properties ?

8. What is reverse osmosis? Mentionone of its practical uses and give anexample for artificial semipermeable
membrane.

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9. Why do electrolytes show abnormal molecular masses? Name the factors
responsible for abnormality.

10. Non-idealsolutions exhibit either positive or negative deviations from Raoult's law. What are these
deviations and why they caused ? Explain with suitable example of each type.

Problems:

1. Calculate the molality and mole fraction of the solute containing 3g of urea (molar mass =60 gmol") per 250
g of water. [Ans: m = 0.2, X, =0.0039]

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2. If 22 g of benzene is dissolved in 122 g of carbon tetrachloride, determine the mass percentage of carbon
tetrachloride (CCI,) and benzene (C;H&). (Ans:mass% of benzene= 15.28, mass% of Chloroform =84.72]

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3. The mole fraction of He in asaturated solution at 20°C is 1.2 x10 - 6. Find the pressure of helium above the
solution. Given Henry's constant at 20°C =144,97 Kbar.

4. The vapour pressure of a pure liquid A is 40 mm Hg at 310 K. The vapour pressure of this liquid in solution
with liquid B is 32mm Hg. Calculate the mole fraction of A in the solution if the mixture obeys Raoult's law. [Ans:
XA = 0.8]

5.Calculate the mass of anon-volatile solute (molar mass 40 g mol) which should be dissolved in 114 g octane
to reduce itsvapour pressure to 80%. [Ans: W; = 8g]

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6. The vapor pressure of 5% aqueous solution of a non-volatile organic substance at 373 Kelvin is 745 mm.
Calculate the molar mass of the solute. (Ans: M, =0.8 gMol]

7. The vapor pressure of water is 92 mm at 323 K. 18.1g of urea are dissolved in 100 g of water the vapor
pressure is reduced by 5 mm.Calculate the molar mass of urea [Ans: 56.7 gMol]

8. Calculate the boiling point of a solution containing 25 g of urea [NH,CONH] and 25 g of thiourea
(NH,CSNH,]in 500-gram chloroform [CHCI,] the boiling point of pure chloroform is 61.2°C and K, is equal to 3.63
Km[Ans: 66.616°c]

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9. Calculate the osmotic pressure in Pascals excreted by a solution prepared by dissolving 1.0g of polymer of
molar mass 185,000 in 450 ml of water is 370 C. (Ans: 30.9 Pa)

10. Calculate the concentration of that solution of sugar which has osmotic pressure of 2.46 atmosphere at 300
K. (Ans: 34.42g/L].

11 Calculatethe molar elevation constant of water, it being given that 0.1 molal aqueous solution of a
substance boiled at 100.052°C. (Ans: Kp= 0.52).

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12. The boiling point of benzene is 353.23 K. When 1.80g of a non-volatile solute was dissolved in 90 gram of
benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of the solute. K, for benzene is 2.53
KKg/mol. (Ans:58 gMol]

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 13.Asolution containing 34.2g of cane Sugar (C,,H,,0,,)dissolved in 500 cm' of water froze at -0.374°C.
Calculate the freezing point depression constant of water. (Ans: K=1.87Km]

14. The solution of urea in water has a boiling point of 100.128°C.Calculate the freezing point of the same
solution. Molal constants for water K; and K, are 1.86°C and 0.512°C respectively. [T, =-0.465°c].

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15. Two elements Aand Bform compounds having formulas AB, and AB,. When dissolved in 20 g of benzene
(CçHs), 1 g of AB, lowers the freezing point by 2.3K,whereas 1.0 g of AB, lowers it by 1.3 K. The molar depression
constant for benzene is 5.1 Kkg mol'. Calculate the atomic masses of Aand B. [Ans: Atomic masses of Aand B
are 25.59 uand 42.64u]

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