Contents Syllabus - etoos india

Topic Page No.

Theory 01 - 02

Exercise - 1 03 - 16




Answer Key 31 - 32

Contents

Syllabus

SOLUTION & COLLIGATIVE PROPERTIES

Raoult�s law; Molecular weight determination from lowering of vapour

pressure, elevation of boiling point and depression of freezing point.

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SOLUTION & COLLIGATIVEPROPERTIES

# 1

SOLUTION AND COLLIGATIVE PROPERTIES

KEY CONCEPT Methods of Expressing the Concentration of a Solution

Normality N = Massof solute ingramsper litreEquivalent massof the solute

Molarity (M) = Mass of the solute in grams per litre

Molecular mass of the solute

Molality (m) = Moles of solute

Weight of solvent (in kg)

Parts per million (ppm) = Mass of solute

Mass of solution x 106

Vapour Pressure of Solutions and Raoult�s Law

The vapour pressure of the solutions of non-volatile solutes can be obtained by applying Raoult�s law.

According to this law. the vapour pressure of a solution containing non-volatUe solute isproportional to mole fraction of the solvent.

For a two component solution A (volatile) and B (non-volatile) the vapour pressure of solution is given byVapour pressure of solution = Vapour pressure of solvent in solution Mole fraction of solvent.

P = PA XA or PA = KXA Þ PA = PAºXA

�For a solution of two or more miscible liquids, the partial vapour pressure of each component is directly

proportional to its mole fraction�.

Total vapour pressure of solution P = PºAXA + PºBXB

The solutions which obey Raoult�s law are called Ideal solutions.

Relative Lowering of Vapour PressurePA = PºA XA PA = vapour pressure of solvent

oA A

0A

P P

P

is called relative lowering of vapour pressure

Ideal Solutions

(i) It should obey Raoult�s law.

i.e. PA = PºAXA and PB = PºBXB

(ii) Hmixture = 0

(iii) Vmixture = 0

Non-ideal Solutions(i) Raoult�s law is not obeyed (ii) Hmixture 0 (iii) Vmixture 0

i.e. PA PºA XA and PB PºBXB



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# 2

Solution with positive deviation(i) PA > PºAXA and PB > PºBXB (ii) Hmixture = + ve (iii) Vmixture = + ve

Solution with negative deviation(i) PA < PAº XA and PB < PB

º XB (ii) Hmixture = � ve (iii) Vmixture = � ve

Azeotrope or azeotropic mixtureA solution which distills without change in composition is called azeotropic mixture or azeotrope.Example of positive deviation - A mixture of nhexane and ethanoL

COLLIGATIVE PROPERTIES(i) Relative lowering of vapour pressure (ii) Elevation of boiling point(iii) Depression of freezing point (iv) Osmotic pressure

Relative Lowering of Vapour Pressure

0A

P

P

= XB = mole fraction of solute

Elevation in Boiling PointTb = KbmWhere Kb is molal elevation constant or molal ebullioscopic constant.

Depression in Freezing PointTf = KfmWhere Kf is molal depression constant.

OSMOTIC PRESSUREThe flow of solvent molecules from a region of higher concentration of solvent to the region of lower

concentration of solvent is termed as the phenomenon of osmosis.

ISOTONIC SOLUTIONThe two solutions having equal osmotic pressure are termed as isotonic solution.

THEORY OF DILUTE SOLUTIONS

=nV

RT

= CRT

Van�t Hoff Factor

Van�t Hoff factor i = Normal molecular mass

Observed molecular mass

i = Observed value of colligative propertyCalculated value of colligative property

a nBi = 1 + (n � 1)

= degree of isonisation



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# 3

PART - I : OBJECTIVE QUESTIONS

* Marked Questions are having more than one correct option.

Section (A) : General Introduction & Types of SolutionA-1. When a crystal of the solute is introduced into a super saturated solution of the solute-

(A) The solute dissolves (B) The excess solute crystallises out(C) The solution becomes unsaturated (D) The solution remains super saturated

A-2. Which does not influence the solubility of a solid in a liquid solvent-(A) Nature of solute (B) Nature of solvent (C) Temperature (D) Pressure

A-3. There are some of the characteristics of the supersaturated solutionI : Equilibrium exists between solutions and solid soluteII : If a crystal of solute is added to supersaturated solution, crystallisation occurs rapidlyIII : Supersaturated solutions contain more solute than they should have at a particular temperatureCorrect characteristics of supersaturated solutions are :(A) I, II, III (B) II, III (C) I, III (D) I, II

A-4. When KCI dissolves in water (assume endothermic dissolution) :(A) H = + ve, S = + ve, G = + ve (B) H = + ve, S= � ve, G = � ve

(C) H = + ve, S = + ve, G = � ve (D) H = � ve, S = � ve, G = + ve

A-5. Which statement best explains the meaning of the phrases "like dissolves like" ?(A) A Solute will easily dissolve a solute of similar mass(B) A solvent and solute with similar intermolecular forces will readily form a solution(C) The only true solutions are formed when water dissolves a non-polar solute(D) The only true solutions are formed when water dissolves a polar solute

A-6. The dissolving process is exothermic when :(A) The energy released in solvation exceeds the energy used in breaking up solute-solute and solvent-

solvent interactions.(B) The energy used in solvation exceeds the energy released in breaking up solute-solute and solvent-

solvent interactions.(C) The energy released in solvation is about the same as the energy used in breaking up solute-solute and

solvent-solvent interactions.(D) The energy used in solvation is about the same as the energy used in breaking up solute-solute and

solvent-solvent interactions.

A-7. Consider the following four liquids :1. Water : highly polar; H-bonding 2. Hexanol : slightly polar ; some H-bonding3. Chloroform : slightly polar; no H-bonding 4. Octane : non-polar ; no H-bondingWhich pair of liquids is immiscible ?(A) Water and octane (B) Water and hexanol(C) Hexanol and chloroform (D) Chloroform and octane

A-8. An ionic compound that attracts atmospheric water so strongly that a hydrate is formed is said to be :(A) Dilute (B) Hygroscopic (C) Immiscible (D) Miscible



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# 4

Section (B) : Expressing Concentration of Solutions

B-1. If 18 gram of glucose (C6H12O6) is present in 1000 gram of an aqueous solution of glucose it issaid to be-(A) 39.2 molal (B) 1.1 molal (C) 0.5 molal (D) 0.1 molal

B-2. Which of the following is correct-

(A) mole = molarity x Vin l = wt

mol wt.

. .(B) milli mole = molarity x Vin mL =

wtmol wt

.. . x 1000

(C) Moles and millimoles of reactants react according to stoichiometric ratio of balanced chemicalequation

(D) All

B-3. Density of water is 1g/mL. The concentration of water in mol/litre is-(A) 1000 (B) 18 (C) 0.018 (D) 55.5

B-4. How many grams of NaOH will be needed to prepare 250 mL of 0.1 M solution-(A) 1 g (B) 10 g (C) 4 g (D) 6 g

B-5. How many grams of glucose should be dissolved to make one litre solution of 10%(w/v) glucose-(A) 10 g (B) 180 g (C) 100 g (D) 1.8 g

B-6. 5.85 g of NaCl are dissolved in 90 g of water. The mole fraction of NaCl is-(A) 0.1 (B) 0.01 (C) 0.2 (D) 0.0196

B-7. The molality of 15% (wt./vol.) solution of H2SO4 of density 1.1 g/cm3 is approximately-(A) 1.2 (B) 1.4 (C) 1.8 (D) 1.6

B-8. 3.0 molal NaOH solution has a density of 1.110 g/ml. The molarity of the solution is-(A) 2.9732 (B) 3.05 (C) 3.64 (D) 3.0504

B-9. In the aqueous solution of sulphuric acid the mole fraction of water is 0.85. The molality of the solutionis-(A) 8.9 m (B) 0.19 m (C) 9.8 m (D) 15 m

B-10. 1000 gram aqueous solution of CaCO3 contains 10 gram of carbonate. Concentration of solution is-(A) 10 ppm (B) 100 ppm (C) 1000 ppm (D) 10,000 ppm

B-11. Equal volumes of 0.1 M AgNO3 and 0.2 M NaCl are mixed. The concentration of NO3� ions in the

mixture will be-(A) 0.1 M (B) 0.05 M (C) 0.2 M (D) 0.15 M

B-12. H2O2 solution used for hair bleaching is sold as a solution of approximately 5.0 g H2O2 per 100 mLof the solution. The molecular weight of H2O2 is 34. The molarity of this solution is approximately-(A) 3.0 (B) 1.5 (C) 0.15 (D) 4.0

B-13. All of the water in a 0.20 M solution of NaCl was evaporated and 0.150 mol of NaCl was obtained.What was the original volume of the sample ?(A) 30 mL (B) 333 mL (C) 750 mL (D) 1000 mL

B-14. 25 mL of 3.0 M HNO3 are mixed with 75 mL of 4.0M HNO3. If the volumes are additive, the molarityof the final mixture would be-(A) 3.25 M (B) 4.0 M (C) 3.75 M (D) 3.50 M

B-15. 10 gram of glucose are dissolved in 150 gram of water. The mass % of glucose is-(A) 5% (B) 6.25% (C) 93.75% (D) 15%

B-16. If 100 ml of 1.0 M NaOH solution is diluted to 1.0 L, the resulting solution contains-(A) 1 mole of NaOH (B) 0.1 mole of NaOH (C) 10.0 mole of NaOH (D) 0.05 mole of NaOH



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# 5

Section (C) : Vapour Pressure of liquid-liquid solution (Raoult's Law)C-1. Pressure cooker reduces cooking time because

(A) the heat is more evenly distributed inside the cooker(B) a large flame is used(C) boiling point of water is elevated(D) whole matter is converted into steam

C-2. The vapour pressures of ethyl alcohol and methyl alcohol are 45 mm Hg and 90 mm Hg. An idealsolution is formed at the same temperature by mixing 60 g of C2H5OH with 40 g of CH3OH. Total vapourpressure of the solution is approximately -(A) 70 mm (B) 35 mm (C) 105 mm (D) 27 mm Hg

C-3. The vapour pressure of water depends upon(A) Surface area of container (B) Volume of container(C) Temperature (D) All

C-4. Among the following substances, the lowest vapour pressure is exerted by -(A) Water (B) Mercury (C) Kerosene (D) Rectified spirit

C-5. Calculate the mole fraction of toluene in the vapour phase which is in equilibrium with a solution of benzeneand toluene having a mole fraction of toluene 0.50. The vapour pressure of pure benzene is119 torr; that of toluene is 37 torr at the same temperature.(A) 0.327 (B) 0.237 (C) 0.732 (D) 0.456

C-6. Benzene and toluene form two ideal solution A and B at 313 K. Solution A (total pressure PA) contains equalmole of toluene and benzene. Solution B contains equal masses of both (total pressure PB). The vapourpressure of benzene and toluene are 160 and 60 mm Hg respectively at 313 K. Calculate the value of PA/PB.(A) 0.694 (B) 0.496 (C) 0.964 (D) 0.732

C-8. The boiling point of C6H6, CH3OH, C6H5NH2 and C6H5NO2 are 80ºC, 650C, 184ºC and 212ºC

respectively. Which will show highest vapour pressure at room temperature-(A) C6H6 (B) CH3OH (C) C6H5NH2 (D) C6H5NO2

C-9. An aqueous solution of methanol in water has vapour pressure �(A) Equal to that of water (B) Equal to that of methanol(C) More than that of water (D) Less than that of water

C-10. Boiling point of water is defined as the temperature at which �(A) Vapour pressure of water becomes equal to that of atmospheric pressure(B) Bubbles are formed(C) Steam comes out(D) None of the above

C-11. A liquid is kept in a closed vessel. If a glass plate (negligible mass) with a small hole is kept on top of theliquid surface, then the vapour pressure of the liquid in the vessel is :(A) More than what would be if the glass plate were removed(B) Same as what would be if the glass plate were removed(C) Less than what would be if the glass plate were removed(D) Cannot be predicted

C-12. A sample of air is saturated with benzene (vapour pressure = 100 mm Hg at 298 K) at 298 K, 750 mm Hgpressure. If it is isothermally compressed to one third of its initial volume, the final pressure of the system is:(A) 2250 torr (B) 2150 torr (C) 2050 torr (D) 1950 torr



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# 6

C-13. The vapor pressures of benzene, toluene and a xylene are 75 Torr, 22 Torr and 10 Torr at 20°C. Which of the

following is not a possible value of the vapor pressure of an equimolar binary/ternary solution of these at20°C? Assume all form ideal solution with each other.

(A) 1

482

(B) 16 (C) 2

353

(D) 1

532

C-14. Consider two liquids A & 8 having pure vapour pressures PºA & PºB forming an ideal solution. The plot ofA

1X

v/s A

1Y (where XA and YYA are the mole fraction of liquid A in liquid and vapour phase respectively) is linear with

slope and Y intercepts respectively :

(A) º

Aº

B

PP and

º º

A Bº

B

(P P )P

(B) º

Aº

B

PP and

º º

B Aº

B

(P P )P

(C) º

Bº

A

PP and

º º

A Bº

B

(P P )P

(D) º

Bº

A

PP and

º º

B Aº

B

(P P )P

C-15. Assuming the formation of an ideal solution, determine the boiling point of a mixture containing 1560 gbenzene (molar mass = 78) and 1125 g chlorobenzene (molar mass = 112.5) using the following against anexternal pressure of 1000 Torr.

(A) 90ºC (B) 100ºC (C) 110ºC (D) 120ºC

C-16. The vapour pressure of water at 20°C is 17.54 mmHg. What will be the vapour pressure of the water in the

apparatus shown after the piston is lowered, decreasing the volume of the gas above the liquid to one half ofits initial volume (assume temperature constant).

(A) 8.77 mmHg (B) 17.54 mmHg(C) 35.08 mmHg (D) between 8.77 and 17.54 mmHg



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# 7

Section (D) : Application of Raoult's Law for volatile solute

D-1. Total vapour pressure of mixture of 1 mol A (pA0 = 150 torr) and 2 mol B (p

B0 = 240 torr) is 200 mm. In

this case :(A) There is positive deviation from Raoult's law(B) There is negative deviation from Raoult's law(C) There is no deviation from Raoult's law(D) Molecular masses of A and B are also required for predicting deviation

D-2. Ideal solution is formed when its components(A) have zero heat of mixing only(B) have zero volume change on mixing only(C) have zero heat of mixing and zero volume change(D) can be converted into gases

D-3. Which of the following is not correct for an ideal solution ?(A) Raoult's law is obeyed for entire concentration range and temperatures(B) Hmix = 0 (C) Vmix = 0 (D) Smix = 0

D-4. Which of the following will form an ideal solution ?(A) C2H5OH and water (B) HNO3 and water(C) CHCl3 and CH3COCH3 (D) C6H6 and C6H5CH3

D-5. Which of the following shows positive deviation from Raoult's law ?(A) C6H6 and C6H5CH3 (B) C6H6 and CCl4(C) CHCl3 and C2H5OH (D) CHCl3 and CH3COCH3

D-6. Which of the following shows negative deviation from Raoult's law ?(A) CHCl3 and acetone (B) CHCl3 and C2H5OH(C) C6H5CH3 and C6H6 (D) C6H6 and CCl4

D-7. A maxima or minima obtained in the temperature composition curve of a mixture of two liquids indicates-(A) an azeotropic mixture(B) an eutectic formation(C) that the liquids are immiscible with one another(D) that the liquids are partially miscible at the maximum or minimum

D-8. Which of the following solution pairs can be separated by fractional distillation ?(A) Water-HNO3 (B) Water-HCl (C) Benzene-toluene (D) C2H5OH-water

D-9. Which of the following is less than zero for ideal solutions ?(A) Hmix (B) Vmix (C) Gmix (D) Smix.

D-10. 100 ml of liquid A and 25 ml of liquid B is mixed to give a solution which does not obey Raoult�s law. The

volume of the solution.(A) will be 125 ml(B) can be > or < than 125 ml(C) can be greater than, equal to or less than 125 ml(D) will be less than 125 ml.

D-11. A solution of sulphuric acid in water exhibits -(A) Negative deviations from Raoult�s law (B) Positive deviations from Raoult�s law

(C) Ideal properties (D) The applicability of Henry�s law

D-12. Binary liquid mixtures which exhibit positive deviations from Raoult�s law boil at ..... temperature than

the expected b.pt -(A) Lower (B) Higher (C) Same (D) Can�t be said



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# 8

D-13. An ideal solution is that which-(A) Shows positive deviation from Raoult's law (B) Shows negative deviation from Raoult's law(C) Has no connection with Raoult's law (D) Obeys Raoult's law

D-14. Which pair shows a contraction in volume on mixing along with evolution of heat-(A) CHCl3 + C6H6 (B) H2O + HCl (C) H2O + HNO3 (D) All

D-15. Azeotropic mixture of water and HCl boils at 381.5 K. By distilling the mixture it is possible to obtain-(A) Pure HCl only (B) Pure water only(C) Neither HCl nor water (D) Both water and HCl in pure state

D-16.* For chloroform and acetone or for a solution of chloroform and acetone if ps (observed (actual)) is comparedwith ps(Theoretical (Raoult)) then which of the following is fare true?

(A) ps(actual) < ps(Raoult) (B) chloroform

0acetone s actualX 0

Limit (p p ) 0

(C) acetone

0chloroform s actualX 0

Limit (p p ) 0

(D) pºacetone > pºchloroform near room temperature

D-17. Given P-x curve for a non-ideal liquid mixture (Fig.). Identify the correct T-x curve for the same mixture.

(A) (B) (C) (D)

Section (E) : Van't Hoff factor

E-1. A complex containing K+, Pt (IV) and Cl� is 100% ionised giving i = 3. Thus, complex is -(A) K2 [PtCl4] (B) K2[PtCl6] (C) K3[PtCl5] (D) K[PtCl3]

E-2. In which case van't Hoff factor is maximum ?(A) KCl, 50% ionised (B) K2SO4 40% ionised(C) FeCl3, 30% ionised (D) SnCl4, 20% ionised

E-3. Which salt may show the same value of Van't Hoff factor (i) as that of K4Fe(CN)6 in very dilute solutionstate-(A) Al2(SO4)3 (B) NaCl (C) Al(NO3)3 (D) Na2SO4

E-4. Which compound corresponds Van't Hoff factor (i) to be equal to 2 in dilute solution-(A) K2SO4 (B) NaHSO4 (C) CH3COOH (D) MgSO4

E-5. In which of the following, the Van't Hoff factor (i) is equal to one-(A) NaCl (B) KNO3 (C) Urea (D) All



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# 9

E-6. The Van't Hoff factor (i) for a dilute aqueous solution of glucose is-(A) zero (B) 1.0 (C) 1.5 (D) 2.0

E-7. Van't Hoff factor (i)-(A) Is less than one in case of dissociation (B) Is more than one in case of association

(C) i = massmolecularobservedmassmolecularnormal

(D) i = massmolecularnormalmassmolecularobserved

E-8. In case of electrolyte which dissociates in solution the Van't Hoff's Factor-(A) > unity (B) < Unity (C) = Unity (D) can be > or < 1

E-9. Which one of the following salts would have the same value of the Van't Hoff factor (i) as that ofK3 [Fe(CN)6].(A) NaCl (B) Na2SO4 (C) Al2(SO4)3 (D) Al(NO3)3

E-10. The van't Hoff factor of a 0.005 M aqueous solution of KCl is 1.95. The degree of ionisation of KCl is(A) 0.95 (B) 0.97 (C) 0.94 (D) 0.96

E-11.* In which of the following pairs of solutions will the values of the Van't Hoft factor be the same?(A) 0.05 M K4 [Fe(CN)6] and 0.10 M FeSO4

(B) 0.10 M K4[Fe(CN)6] and 0.05 M FeSO4 . (NH4)2S04. 6H2O(C) 0.20 M NaCI and 0.10 M BaCI2

(D) 0.05 M FeSO4 . (NH4)2SO4 . 6H2O and 0.02 M KCI . MgCI2 .6H2O

E-12. A solute 'S' undergoes a reversible trimerization when dissolved in a certain solvent. The boiling pointelevation of its 0.1 molal solution was found to be identical to the boiling point elevation in case of a0.08 molal solution of a solute which neither undergoes association nor dissociation. To what percenthad the salute'S' undergone trimerization?(A) 30% (B) 40% (C) 50% (D) 60%

E-13. Barium ions, CN� and Co2+ form an ionic complex. If that complex is supposed to be 75% ionised inwater with Van't Hoff factor ' i ' equal to four, then the coordination number of Co2+ in the complex canbe:(A) Six (B) Five (C) Four (D) Six and Four both

E-14.* Dry air is slowly passed through three solutions of different concentrations, c1, c2 and c3 ; each containing(non volatile) NaCI as solute and water as solvent, as shown in the Fig. If the vessel 2 gains weight andthe vessel 3 loses weight, then :

(A) c1 > c2 (B) c1 < c2 (C) c1 < c3 (D) c2 > c2

E-15. At a constant temperature, S will be maximum for which of the following processes :(A) Vaporisation of a pure solvent(B) Vaporisation of solvent from a solution containing nonvolatile and nonelectrolytic solute in it(C) Vaporisation of solvent from a solution containing nonvolatile but electrolytic solute in it(D) Entropy change will be same in all the above cases



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# 10

Section (F) Raoult's law for non-volatile solute

F-1. Vapour pressure of a solvent containing nonvolatile solute is -(A) More than the vapour pressure of a solvent(B) Less than the vapour pressure of solvent(C) Equal to the vapour pressure of solvent(D) None of these

F-2. The relative lowering in vapour pressure is-

(A) Xsolute (B) 1

Xsolute(C) = Xsolute (D) m

F-3. The vapour pressure of pure liquid solvent A is 0.80 atm. When a non-volatile substance B is added tothe solvent, its vapour pressure drops to 0.60 atm. mol fraction of the component B in the solution is -(A) 0.50 (B) 0.25 (C) 0.75 (D) 0.40

F-4. The vapour pressure of a solution having solid as solute and liquid as solvent is -(A) directly proportional to mole fraction of the solvent(B) inversely proportional to mole fraction of the solvent(C) directly proportional to mole fraction of the solute(D) inversely proportional to mole fraction of the solute

F-5. The vapour pressure of a dilute aqueous solution of glucose is 750 mm of mercury at 373 K. The molefraction of solute is -

(A) 1

10(B)

1

7 6.(C)

1

35(D)

1

76

F-6. The vapour pressure of pure liquid A is 10 torr and at the same temperature when 1 g of B solid isdissolved in 20 g of A, its vapour pressure is reduced to 9.0 torr. If the molecular mass of A is 200 amu,then the molecular mass of B is -(A) 100 amu (B) 90 amu (C) 75 amu (D) 120 amu

F-7. At 25°C, the vapour pressure of methyl alcohol is 96.0 torr. What is the mole fraction of CH3OH in a solutionin which the (partial) vapor pressure of CH3OH is 23.0 torr at 25°C?

(A) 0.24 (B) 0.42 (C) 0.62 (D) 0.84

F-8. The vapour pressure of pure water at 25°C is 23.76 torr. The vapour pressure of a solution containing 5.40 g

of a nonvolatile substance in 90.0 g water is 23.32 torr. Compute the molecular weight of the solute.(A) 37 g/mol (B) 57 g/mol (C) 47 g/mol (D) 67 g/mol

F-9. Calculate the relative lowering in vapour pressure if 100 g of a nonvolatile solute (mol.wt.100) are dissolved in432 g water.(A) 0.02 (B) 0.03 (C) 0.04 (D) 0.01

F-10. The vapour pressure of pure benzene at 25° C is 639.7 mm of Hg and the vapour pressure of a solution of a

solute in C6H6 at the same temperature is 631.7 mm of Hg. Calculate molality of solution.(A) 0.16 m (B) 0.25 m (C) 0.37 m (D) 0.42 m

F-11. The vapour pressure of water is 17.54 mm Hg at 293 K. Calculate vapour pressure of 0.5 molal solution of asolute in it.(A) 17.6 (B) 17.38 (C) 17.12 (D) 16.58



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# 11

Section (G) : Elevation in Boiling Point & Depression in Freezing Point

G-1. PtCl4 . 6H2O can exist as a hydrated complex 1 molal aq. solution has depression in freezing point of3.72°. Assume 100% ionisation and Kf(H2O) = 1.86° mol�1 kg, then complex is -(A) [Pt(H2O)6]Cl4 (B) [Pt(H2O)4Cl2]Cl2 . 2H2O(C) [Pt(H2O)3Cl3]Cl . 3H2O (D) [Pt(H2O)2Cl4] . 4H2O

G-2. Maximum freezing point will be for 1 molal solution of, assuming equal ionisation in each case -(A) [Fe(H2O)6]Cl3 (B) [Fe(H2O)5Cl]Cl2 . H2O(C) [Fe(H2O)4Cl2]Cl . 2H2O (D) [Fe(H2O)3Cl3] . 3H2O

G-3. A solution of 1.25 g of non-electrolyte in 20 g of water freezes at 271.94 K. If Kf is 1.86 K kg mol�1 thenmolecular mass of the solute will be -(A) 207.8 (B) 179.79 (C) 209.6 (D) 109.5

G-4. The freezing point order of the solution of glucose in water is -(A) 10% > 3% > 2% > 1% (B) 1% > 2% > 3% > 10%(C) 1% > 3% > 10% > 2% (D) 10% > 1% > 3% > 2%

G-5. The freezing point of equimolal aqueous solution will be highest for -(A) C6H5NH3Cl (B) Ca(NO3)2 (C) La(NO3)3 (D)C6H12O6

G-6. The molal elevation constant of water is 0.51. The boiling point of 0.1 molal aqueous NaCl solution isnearly -(A) 100.05°C (B) 100.1°C (C) 100.2°C (D) 101.0°C

G-7. Solute when dissolved in water -(A) Increases the vapour pressure of water (B) Decreases the boiling point of water(C) Decreases the freezing point of water (D) All of the above

G-8. The elevation of boiling point method is used for the determination of molecular weight of -(A) Non-volatile and soluble solute (B) Non-volatile and insoluble solute(C) Volatile and soluble solute (D) Volatile and insoluble solute

G-9. Which statement is correct for the boiling point of solvent containing a dissolved solid substance-(A) Boiling point of the liquid is depressed(B) Boiling point of the liquid is elevated(C) There is no effect on the boiling point(D) The change depends upon the polarity of the liquid

G-10. In cold countries, ethylene glycol is added to water in the radiators of cars during winters. Itresults in -(A) Lowering in boiling point (B) Reducing viscosity(C) Reducing specific heat (D) Lowering in freezing point

G-11. The molal elevation/depression constant depends upon-(A) Nature of solvent (B) Nature of solute (C) Temperature (D) H solution

G-12. An example of colligative property is-(A) Freezing point (B) Boiling point (C) Vapour pressure (D) Osmotic pressure

G-13. The molal elevation constant is the ratio of the elevation in BP to-(A) Molarity (B) Molality (C) Mole fraction of solute(D) Mole fraction of solvent



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G-14. Observe the P-T phase diagram for a given substance A. Then melting point of A(s), boiling point of A(I),critical point of A and triple point of A (at their respective pressures) are respectively :

(A) T1, T2, T3, T4 (B) T4, T3, T1, T2 (C) T3, T4, T2, T1 (D) T2, T1, T3, T4

Section (H) : Osmotic Pressure

H-1. Which inorganic precipitate acts as semipermeable membrane ?(A) calcium sulphate (B) barium oxalate (C) nickel phosphate (D) copper ferrocyanide

H-2. At constant temperature, the osmotic pressure of a solution is -(A) directly proportional to the concentration of solute(B) inversely proportional to the concentration(C) directly proportional to the square of concentration(D) directly proportional to the square root of concentration

H-3. If 0.1 M solution of glucose and 0.1 M urea solution are placed on two sides of a semipermeablemembrane to equal heights, then it will be correct to say that -(A) there will be no net movement across the membrane(B) glucose will flow towards urea solution(C) urea will flow towards glucose solution(D) water will flow from urea solution towards glucose solution

H-4. A solution of a substance containing 1.05 g per 100 mL. was found to be isotonic with 3% glucosesolution. The molecular mass of the substance is -(A) 31.5 (B) 6.3 (C) 630 (D) 63

H-5. The osmotic pressure of equimolar solutions of BaCl2, NaCl and glucose will be in the order(A) glucose > NaCl > BaCl2 (B) BaCl2 > NaCl > glucose(C) NaCl > BaCl2 > glucose (D) NaCl > glucose > BaCl2

H-6. At 300 K, two solutions of glucose in water of concentration 0.01 M and 0.001 M are separated bysemipermeable membrane. Pressure needs to be applied on which solution, to prevent osmosis? Calculatethe magnitude of this applied pressure.(A) 0.22 (B) 0.11 (C) 0.33 (D) 0.44

H-7. The passing of particles through semipermeable membrane is called -(A) Osmosis (B) Electrodialysis (C) Electrophoresis (D) Electroplating

H-8. In the case of osmosis, solvent molecules move from-(A) Higher vapour pressure to lower vapour pressure(B) Higher concentration to lower concentration(C) Lower vapour pressure to higher vapour pressure(D) Higher osmotic pressure to lower osmotic pressure



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H-9. If mole fraction of the solvent in a solution decreases then-(A) Vapour pressure of solution increases (B) b.pt decreases(C) Osmotic pressure increases (D) All are correct

H-10. Two solutions have different osmotic pressures. The solution of higher osmotic pressure is called-(A) Isotonic solution (B) Hypotonic solution (C) Isotopic solution (D) Hypertonic solution

H-11. According to Boyle-Vant Hoff law for solutions, the osmotic pressure of a dilute solution is-(A) Inversely proportional to its volume (B) Directly proportional to its volume(C) Equal to its volume (D) None of the above

H-12. Which statement is incorrect about osmotic pressure (), volume (V) and temperature (T)-

(A) 1V

if T is constant (B) T if V is constant

(C) V if T is the constant (D) V is constant if T is constant

H-13. Osmotic pressure of a solution increases by-(A) Decreasing the temperature(B) Increasing the volume(C) Increasing the number of molecules of the solute(D) None of the above

H-14. An electrolyte A gives 3 ions and B is a non-electrolyte. If 0.1 M solution of B produces an osmoticpressure P, then 0.05 M solution of A will produce an osmotic pressure, assuming that the electrolyteis completely ionised -(A) 1.5 P (B) P (C) 0.5 P (D) 0.75 P

H-15. Two beakers, one containing 20 ml of a 0.05 M aqueous solution of a non volatile, non electrolyte andthe other, the same volume of 0.03 M aqueous solution of NaCI, are placed side by side in a closedenclose. What are the volumes in the two beakers when equation is attached? Volume of the solutionin the first and second beaker are respectively.(A) 21.8 ml and 18.2 mL (B) 18.2 mL and 21.8 mL(C) 20 mL and 20 mL (D) 17.1 mL and 22.9mL

Section (I) : Solutions of gases in liquids

I-1. The solubility of gases in liquids :(A) increases with increase in pressure and temperature(B) decreases with increase in pressure and temperature(C) Increases with increase in pressure and decrease in temperature(D) decreases with increase in pressure and increase in temperature

I-2. The solubility of N2 (g) in water exposed to the atmosphere, when the partial pressure is 593 mm is5.3 x 10�4 M. Its solubility at 760 mm and at the same temperature is :(A) 4.1 × 10�4 M (B) 6.8 × 10�4 M (C) 1500 M (D) 2400 M

I-3. Some of the following gases are soluble in water due to formation of their ions :I : CO2; II : NH3 ; III : HCI ; IV : CH4; V : H2Water insoluble gases can be :(A) I, IV , V (B) I, V (C) I, II, III (D) IV, V

I-4.* Select correct statements :(A) Gases which have high value of VanderWaals constant 'a' are easily liquefied(B) Easily liquefiable gases are water soluble(C) Ions forming gases in a solvent are soluble in that solvent(D) Under same conditions, NH3 has low solubility than that of CO2



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I-5. Select incorrect statement :(A) Higher the value of kH(Henry's law constant) at a given pressure, the lower is the solubility of the gas in

the liquid(B) Solubility of a gas in a liquid decreases with increases in temperature and pressure(C) To minimise the painful effects accompanying the decompression of deep sea divers, O2 diluted with

less soluble He gas is used as breathing gas(D) The solubility of a gas in a liquid is governed by Henry's law

I-6.* According to Henery's law, the partial pressure of gas (Pi) is directly proportional to mole fraction of gas indissolved state, i.e., Pgas = KH . Xgas ; where KH is Henry's constant. Which are correct?(A) KH is characteristic constant for a given gas-solvent system(B) Higher is the value of KH, lower is solubility of gas for a given partial pressure of gas(C) KH has temperature dependence(D) KH increases with temperature

PART - II : MISCELLANEOUS OBJECTIVE QUESTIONS

Comprehensions :

Comprehension # 1Vapour pressure of a solvent is the pressure exerted by vapours when they are in equilibrium with itssolvent at that temperature. The vapour pressure of solvent is dependent on nature of solvent,temperature, addition of non-volatile solute as well as nature of solute to dissociate or associate. Thevapour pressure of a mixture obtained by mixing two volatile liquids is given by PM = PºA . XA + PºB .XB where PºA and PºB are vapour pressures of pure components A and B and XA, XB are their mole fractionin mixture. For solute-solvent system, the relation becomes PM = PºA . XA where B is non-volatile solute.

1. The vapour pressure of benzene and its solution with a non-electrolyte are 640 and 600 mm respectively.The molality of the solution is -(A) 0.80 (B) 0.86 (C) 0.90 (D) 0.95

2. A mixture of two volatile liquids A and B for 1 and 3 moles respectivley has a V.P. of 300 mm at 27ºC.

If one mole of A is further added to this solution, the vapour pressure becomes 290 mm at 27ºC. The

vapour pressure of pure A is -(A) 250 mm (B) 316 mm (C) 220 mm (D) 270 mm

3. The amount of solute (mol. wt. 60) required to dissolve in 180 g of water to reduce the vapour pressureto 4/5 of the pure water -(A) 120 g (B) 150 g (C) 200 g (D) 60 g



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Passage # 2 :

Consider some facts about the above phase diagram :

Vapour pressure diagram for real solutions of two liquids A and B that exhibit a positive deviation fromRaoult's law. The vapour pressure of both A and B are greater than predicted by Raoult's law. Thedashed lines represented the plots for idealsolutions.

4. A : This is observed when A.....B attractions are greater than average of A.....B and B.... Battraction:B : Hmix = + ve, Vmax = + veC : Boiling point is smaller than expected such that vaporisation is increasedD : Mixture is called azeotropic mixtureSelect correct facts(A) A, B, C (B) B, C, D (C) A, C, D (D) A, B, C, D

5. Total vapour pressure of mixture of 1 mol of volatile component A (pº A = 100 mmHg) and 3 mol of

volatile component B (pºB = 60 mmHg) is 75 mm. For such case :(A) There is positive deviation from Raoult's law(B) Boiling point has been lowered(C) Force of attraction between A and B is smaller than that between A and A or between Band B.(D) All the above statements are correct.

Assertion / Reasoning

DIRECTIONS :Each question has 5 choices (A), (B), (C), (D) and (E) out of which ONLY ONE is correct.(A) Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.(B) Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1.(C) Statement-1 is True, Statement-2 is False.(D) Statement-1 is False, Statement-2 is True.(E) Statement-1 and Statement-2 both are False.

6. Statement - I. Addition of a non-volatile solute causes a depression in vapour pressure.Statement - II. Vapour pressure of a solution is directly proportional to mole fraction of solvent.

7. Statement - I. 0.02 m solutions of urea and sucrose will freeze at same temperature.Statement - II. Freezing point of a solution is inversely proportional to the concentration of solution.

8. Statement - I. For isotonic solutions C1 = C2Statement - II. For isotonic solutions 1 = 2

9. Statement - I. Benzene-toluene mixture forms ideal solution at low concentrations.Statement - II. Components with structural similarity forms ideal solution in general.



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10. Statement - I. Dissolution of sulphuric acid in water gives a solution which shows negative deviation.Statement - II. The solutions which have same vapour pressure at a given temperature are calledisotonic solutions.

11. Statement - I. Greater the molal depression constant of the solvent used less is the freezing pointof the solution.Statement - II. Depression in freezing point depends upon the nature of the solvent.

12. Statement - I. Vant Hoff factor for electrolytes is always geater than unity.Statement - II. The no. of particles increases in solution due to electrolytic dissociation.

13. Statement - I. The vapour pressure of 0.1 M sugar solution is more than that of 0.1 M potassiumchloride solution.Statement - II. Lowering of vapour pressure is directly proportional to the no. of species present inthe solution.

14. Statement - I. Blood cells are isotonic with 0.16 M NaCl solution.Statement - II. Cell wall of blood cells acts as semi-permeable membrane.

15. Statement - I. Molarity of the solution changes with temperature.Statement - II. Molarity is a colligative property.

Match the Column Type

Match the following columns :

16. Column I Column IIA. Ideal solution P. Solute-solvent interactions are weaker than

solute-solute

B. Solutions showing positive deviations Q. Solute-solvent interactions are similarto solute-solute

C. Solutions showing negative deviations R. Solute-solvent interactions are strongerthan solute-solute interactions

PART - I : OBJECTIVE QUESTIONS

* Marked Questions are having more than one correct option.1. FeCl3 on reaction with K4[Fe(CN)6] in aq. solution gives blue colour. These are separated by a

semipermeable membrane PQ as shown. Due to osmosis there is -

(A) blue colour formation in side X (B) blue colour formation in side Y(C) blue colour formation in both of the sides X and Y (D) no blue colour formation



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2. Which has maximum osmotic pressure at temperature T :(A) 100 mL of 1 M urea solution(B) 300 mL of 1 M glucose solution(C) mixture of 100 mL of 1 M urea solution and 300 mL of 1 M glucose solution(D) all are isotonic

3. Osmotic pressure of blood is 7.40 atm at 27°C. Number of mol of glucose to be used per L for an

intravenous injection that is to have the same osmotic pressure as blood is -(A) 0.3 (B) 0.2 (C) 0.1 (D) 0.4

4. Consider following cases -I : 2M CH3COOH solution in benzene at 27°C where there is dimer formation to the extent of 100%.

II : 0.5 M KCl aq. solution at 27°C, which ionises 100%.

Which is/are true statements(s) -(A) both are isotonic (B) is hypertonic (C) II is hypotonic (D) none is correct

5. pH of a 0.1 M monobasic acid is found to be 2. Hence its osmotic pressure at a given temp. T K is-(A) 0.1 RT (B) 0.11 RT (C) 1.1 RT (D) 0.01 RT

6. Mol fraction of the component A in vapour phase is x1 and mol fraction of component A in liquid mixture

is x2 then (pA0 = vapour pressure of pure A ; p

B0 = vapour pressure of pure B), then total vapour pressure

of the liquid mixture is -

(A) p x

xA0

2

1(B)

p x

xA0

1

2(C)

p x

xB0

1

2(D)

p x

xB0

2

1

7. Equal volumes of M/20 urea solution and M/20 glucose solution are mixed. The mixture wil have osmoticpressure.(A) equal to either of the solution (B) less than either of the solution(C) higher than either of the solution (D) zero

8. When mercuric chloride is added to the aqueous solution of potassium iodide -(A) The boiling point does not change (B) Freezing point is raised(C) The freezing point is lowered (D) Freezing point does not change

9. The molecular weight of benzoic acid in benzene as determined by depression in freezing point methodcorresponds to -(A) Ionisation of benzoic acid (B) Dimerization of benzoic acid(C) Trimerization of benzoic acid (D) Solvation of benzoic acid

10. Two liquids A and B have PA0 : P

B0 = 1 : 3 at a certain temperature. If the mole fraction ratio of

xA : xB = 1 : 3, the mole fraction of A in vapour in equilibrium with the soltuion at a given temperature is:(A) 0.1 (B) 0.2 (C) 0.5 (D) 1.0

11. The diagram given below is a vapour pressure composition diagram for a binary solution of A and B. Inthe solution, A � B interactions are -

(A) Similar to A � A and B � B interactions (B) Greater than A � A and B � B interactions

(C) Smaller than A � A and B � B interactions (D) Unpredictable



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12. To 10 ml of 1 M BaCl2 solution 5 ml of 0.5 M K2SO4 is added, BaSO4 is precipitated out. What willhappen for the remaining liquid -(A) Freezing point is increased (B) No change in Boiling Point(C) Freezing point is lowered (D) Boiling Point is lowered

13. Two solutions of KNO3 and CH3COOH are prepared separatedly. Molarity of both is 0.1 M and osmoticpressures are P1 and P2 respectively. The correct relationship between the osmotic pressures is -

(A) P2 > P1 (B) P1 = P2 (C) P1 > P2 (D) 21

1

PPP

= 21

2

PPP

14. The highest temperature at which vapour pressure of a liquid can be measured is -(A) Boling point of liquid (B) Critical temperature (Tc)(C) Critical solution temperature (D) Inversion temperature

15. Equimolal solutions of A and B show depression in freezing point in the ratio 2 : 1. A remains in itsnormal state in solution. B will be ........... in solution -(A) Normal (B) Dissociated (C) Associated (D) Hydrolysed

16. Solubility curves of four ionic salts X, Y, Z, W are given below :

In which case the value of Hsol. < 0(A) X (B) Y (C) Z (D) W.

17. The vapour pressure of the solution of two liquids A(pº = 80 mm) and B(pº = 120 mm) is found to be 100

mm when xA = 0.4. The result shows that(A) solution exhibits ideal behaviour(B) solution shows positive deviations(C) solution shows negative deviations(D) solution will show positive deviations for lower concentration and negative deviations for higher

concentrations.

18. The diagram given below represents boiling point composition diagram of solution of component A andB, what is true among the following?

(A) The solution shows negative deviation (B) A-B-interactions are stronger than A-A and B-B(C) The solution is ideal solution (D) The solution shows positive deviation.

19. At higher altitudes, water boils at temperature < 100ºC because

(A) temperature of higher altitudes is low (B) atmospheric pressure is low(C) the proportion of heavy water increases (D) atmospheric pressure becomes more.



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20. After dissolving the outer shell of the egg in acetic acid, it is put in distilled water. Which of thefollowing is true?(A) The size of the egg will decrease (B) The size of the egg will increase.(C) The size of the egg will remain the same. (D) It will first shrink and then start enlarging.

21. Two elements A and B form compounds having molecular formulae AB2 and AB4. When dissolved in20.0 g of Benzene, 1.00 g of AB2 lowers f.p. by 2.3ºC whereas 1.00 g of AB4 lowers f.p. by 1.3ºC. The

molal depression constant for benzene is 5.1. The atomic masses of A and B are respectively(A) Cannot be determine (B) 42.6, 25.5(C) 30.60 (D) 25.5, 42.6

22. Arrange the following aqueous solutions in the order of their increasing boiling points(i) 0.001 M NaCl (ii) 0.001 M urea (iii) 0.001 M MgCl2 (iv) 0.01 M NaCl(A) ii < i < iii < iv (B) i < ii < iv < iii (C) ii < i = iii < iv (D) iv < iii < i < ii.

23. Osmotic pressure of 30% solution of glucose is 1.20 atm and that of 3.42% solution of cane sugar is2.5 atm. The osmotic pressure of the mixture containing equal volumes of the two solutions will be(A) 2.5 atm (B) 3.7 atm (C) 1.85 atm (D) 1.3 atm.

24. Relative decrease in vapour pressure of an aqueous solution containing 2 mol NaCl in 3 mol H2O is 0.6.On reaction with AgNO3, this solution will form(A) 1 mole AgCl (B) 0.25 mole AgCl (C) 2 mole AgCl (D) 0.50 mole AgCl.

25. A 1% aqueous solution (W/V) of a certain substance is isotonic with 3% solution of glucose (M Mass180). The molecular mass of the substance is(A) 60 (B) 120 (C) 180 (D) 360

26. The aqueous solution that has the lowest vapour pressure at a given temperature is(A) 0.1 molal sodium phosphate (B) 0.1 molal barium chloride(C) 0.1 molal sodium chloride (D) 0.1 molal glucose

27. In a binary solution of two liquids A and B, xA and yB are mol fractions of A in liquid and vapour phase.What is correct.

(A) xA + yA = 1 (B) y

A

x

x = 10

(C) Ax1

is linear function of yA (D) xA�1 is linear function of yA

�1.

28. 20 ml of barium chloride solution requires 10 ml of 0.4 AgNO3 solution for complete precipitation ofAgCl. The osmotic pressure of barium chloride solution assuming complete ionisation at 27ºC will be

(A) 7.38 atm (B) 4.5 atm (C) 2.46 atm (D) unpredictable.

29. A solution containing 28 g of phosphorus in 315 g CS2 (b.p. 46.3ºC) boils at 47.98ºC. If Kb for CS2 is2.34 K kg mol�1. The formula of phosphorus is (at. mass of P = 31).(A) P6 (B) P4 (C) P3 (D) P2.

30. Mixture of volatile components A and B has total vapour pressure (in torr)p = 254 � 119 xA

where xA is mol fraction of A in mixture. The values of pºA and p0B (in torr) are

(A) 254, 119 (B) 119, 254 (C) 135, 254 (D) 154, 119



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# 20

31. For an ideal binary liquid solution with

AP >

BP , which relation between XA (mole fraction of A in liquid phase)

and YA(mole fraction of A in vapour phase) is correct?

(A) YA < YB (B) XA > XB (C) B

A

B

A

X

X

Y

Y (D)

B

A

B

A

X

X

Y

Y

32. A 0.001 molal solution of a complex [MA8] in water has the freezing point of �0.0054°C. Assuming 100%

ionization of the complex salt and Kf for H2O = 1.86 km�1, write the correct representation for the complex(A) [MA8] (B) [MA7]A (C) [MA6]A2 (D) [MA5]A3

33. Assuming each salt to be 90 % dissociated, which of the following will have highest boiling point?(A) Decimolar Al2(SO4)3(B) Decimolar BaCl2(C) Decimolar Na2SO4(D) A solution obtained by mixing equal volumes of (B) and (C)

34. The vapour pressure of a solvent decreased by 10 mm of Hg when a non-volatile solute was added to thesolvent. The mole fraction of solute in solution is 0.2, what would be mole fraction of the solvent if decreasein vapour pressure is 20 mm of Hg(A) 0.2 (B) 0.4 (C) 0.6 (D) 0.8

35. Elevation of boiling point of 1 molar aqueous glucose solution (density = 1.2 g/ml) is(A) Kb (B) 1.20 Kb (C) 1.02 Kb (D) 0.98 Kb

36. What will be the molecular weight of CaCl2 determined in its aq. solution experimentally from depression offreezing point?(A) 111 (B) < 111 (C) > 111 (D) data insufficient

37. 1.0 molal aqueous solution of an electrolyte A2B3 is 60% ionised. The boiling point of the solution at 1 atm is

(1

)OH(b molkgK52.0K2

)

(A) 274.76 K (B) 377 K (C) 376.4 K (D) 374.76 K

38. Which of the following plots represents an ideal binary mixture?(A) Plot of Ptotal v/s 1/XB is linear (XB = mole fraction of 'B' in liquid phase).(B) Plot of Ptotal v/s YA is linear (YA = mole fraction of 'A' in vapour phase)

(C) Plot oftotalP

1 v/s YYA is linear

(D) Plot of totalP

1 v/s YB is non linear

39. Pressure over ideal binary liquid mixture containing 10 moles each of liquid A and B is gradually decreased

isothermally. If oAP =200 mm Hg and o

BP =100 mm Hg, find the pressure at which half of the liquid is converted

into vapour.(A) 150 mm Hg (B) 166.5 mm Hg (C) 133 mm Hg (D) 141.4 mm Hg

40. Two liquids A & B form an ideal solution. What is the vapour pressure of solution containing 2 moles of A and

3 moles of B at 300 K? [Given : At 300 K, Vapour pr. of pure liquid A ( oAP ) = 100 torr, Vapour pr. of pure liquid

B ( oBP ) = 300 torr]

(A) 200 torr (B) 140 torr (C) 180 torr (D) None of these



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# 21

41. Which of the following represents correctly the changes in thermodynamic properties during the formationof 1 mol of an ideal binary solution.

(A) (B)

(C) (D)

42. A liquid mixture having composition corresponding to point z in the figure shown is subjected to distillation atconstant pressure. Which of the following statement is correct about the process :

(A) The composition of distillate differs from the mixture(B) The boiling point goes on changing(C) The mixture has highest vapour pressure than for any other composition.(D) Composition of an azeotrope alters on changing the external pressure.

43. The vapour pressure of a saturated solution of sparingly soluble salt (XCl3) was 17.20 mm Hg at 27°C. If the

vapour pressure of pure H2O is 17.25 mm Hg at 300 K, what is the solubility of sparingly soluble salt XCl3 inmole/Litre.(A) 4.04 × 10�2 (B) 8.08 ×10�2 (C) 2.02 × 10�2 (D) 4.04 × 10�3

44. At 300 K, the vapour pressure of an ideal solution containing 3 mole of A and 2 mole of B is 600 torr. At thesame temperature, if 1.5 mole of A & 0.5 mole of C (non-volatile) are added to this solution the vapour

pressure of solution increases by 30 torr. What is the value of oBP ?

(A) 940 (B) 405 (C) 90 (D) none of these

45. The following graph represents variation of boiling point with composition of liquid and vapours of binaryliquid mixture. The graph is plotted at constant pressure.Which of the following statement(s) is incorrect. Here X & Y stands for mole fraction in liquid and vapourphase respectively

(A) Xbenzene = 0.5 and Ytoluene = 0.2 (B) Xtoluene = 0.3 and Ybenzene = 0.6(C) Xbenzene = 0.3 and Ytoluene = 0.4 (D) if Xbenzene = 0.7 than Ytoluene < 0.3



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# 22

46. The freezing point depression of a 0.1 M aq. solution of weak acid (HX) is �0.20°C.

What is the value of equilibrium constant for the reaction?HX (aq) H+(aq) + X¯ (aq) [Given : Kf for water = 1.8 kg mol�1 K. & Molality = Molarity ](A) 1.46×10�4 (B) 1.35 × 10�3 (C) 1.21 × 10�2 (D) 1.35 × 10�4

47. The van�t Hoff factor for 0.1 M Ba(NO3)2 solution is 2.74. The degree of dissociation is(A) 91.3% (B) 87% (C) 100% (D) 74%

48. The vapour pressure of an aqueous solution is found to be 750 torr at certain temperature 'T'. If 'T' is thetemperature at which pure water boils under atmospheric pressure and same solution show elevation inboiling point Tb = 1.04 K, find the atmospheric pressure (Kb = 0.52 K kg mol�1 )(A) 777 (B) 779 (C) 782 (D) 746

49. Select correct statement -(A) b.p. of 1 molal NaCl solution is twice that of 1 molal sucrose solution(B) b.p. elevation of 1 molal glucose solution is half of the 1 molal KCl solution(C) b.p. is a colligative property(D) All of the above

PART - II : SUBJECTIVE QUESTIONS

1. An aqueous solution containing 288 gm of a non-volatile compound having the stoichiometric compositionCxH2xOx in 90 gm water boils at 101.24°C at 1.00 atmospheric pressure. What is the molecular formula?

Kb(H2O) = 0.512 K mol�1 kg ; Tb(H2O) = 100°C

2. The degree of dissociation of Ca(NO3)2 in a dilute aqueous solution containing 7 gm of the salt per100 gm of water at 100°C is 70%. If the vapour pressure of water at 100°C is 760 mm. Calculate the vapour

pressure of the solution.

3. The addition of 3 gm of substance to 100 gm CCl4(M = 154 gm mol�1) raises the boiling point of CCl4 by0.60°C of Kb (CCl4) is 5.03 kg mol�1 K. Calculate(a) the freezing point depression(b) the relative lowering of vapour pressure(c) the osmotic pressure at 298 K(d) the molar mass of the substanceGiven Kf(CCl4) = 31.8 kg mol�1K and (density) of solution = 1.64 gm/cm3

4. A 10% solution of cane sugar has undergone partial inversion according to the reaction:Sucrose + Water Glucose + Fructose. If the boiling point of solution is 100.27°C.

(a) What is the average mass of the dissolved materials?(b) What fraction of the sugar has inverted? Kb(H2O) = 0.512 K mol�1 kg

5. Sea water is found to contain 5.85% NaCl and 9.50% MgCl2 by weight of solution. Calculate its normal boilingpoint assuming 80% ionisation for NaCl and 50% ionisation of MgCl2 [Kb(H2O) = 0.51kgmol1K].

6. The latent heat of fusion of ice is 80 calories per gram at 00C. What is the freezing point of a solution of KClin water containing 7.45 grams of solute in 500 grams of water, assuming that the salt is dissociated to theextent of 95%?

7. The molar volume of liquid benzene (density = 0.877 g ml1) increases by a factor of 2750 as it vaporizes at

20°C and that of liquid toluene (density = 0.867gml1) increases by a factor of 7720 at 20°C.

Solution of benzene & toluene has a vapour pressure of 46.0 torr. Find the mole fraction of benzene in thevapour above the solution.



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# 23

8. At 100oC, benzene & toluene have vapour pressure of 1375 & 558 Torr respectively. Assuming these two forman ideal binary solution, calculate the composition of the solution that boils at 1 atm & 100oC. What is thecomposition of vapour issuing at these conditions?

9. Calculate the boiling point of a solution containing 0.61g of benzoic acid in 50g of carbon disulphide assuming84% dimerization of the acid. The boiling point and Kb of CS2 are 46.2°C and 2.3 K kg mol�1, respectively.

10. At 25OC, 1 mol of A having a vapor pressure of 100torr and 1 mol of B having a vapor pressure of 300 torr were

mixed. The vapor at equilibrium is removed, condensed and the condensate is heated back to 25OC. Thevapors now formed are again removed, recondensed and analyzed. What is the mole fraction of A in this

condensate?

11. Phenol associates in benzene to a certain extent to form a dimer. A solution containing 20 × 10�3 kg phenolin 1 kg of benzene has its freezing point depressed by 0.69 K. Calculate the fraction of phenol that hasdimerised. Kf for benzene = 5.12 kg mol�1K.

12. 30 ml of CH3OH (d = 0.7980 gm cm�3) and 70 ml of H2O (d=0.9984 gm cm�3) are mixed at 25°C to form a

solution of density 0.9575 gm cm�3. Calculate the freezing point of the solution. Kf (H2O) is1.86 kg mol�1 K. Also calculate its molarity.

13. Dry air was drawn thorugh bulbs containing a solution of 40 grams of urea in 300 grams of water, then throughbulbs containing pure water at the same temperature and finally through a tube in which pumice moistenedwith strong H2SO4 was kept. The water bulbs lost 0.0870 grams and the sulphuric acid tube gained 2.036grams. Calculate the molecular weight of urea.

14. Vapour pressure of C6H6 and C7H8 mixture at 500C is given by P (mm Hg) = 180 XB + 90, where XB is the molefraction of C6H6. A solution is prepared by mixing 936g benzene and 736g toluene and if the vapours over thissolution are removed and condensed into liquid and again brought to the temperature of 500C, what would bemole fraction of C6H6 in the vapour state?

15. When the mixture of two immicible liquids (water and nitrobenzene) boils at 372 K and the vapour pressureat this temperature are 97.7 kPa (H2O) and 3.6 kPa (C6H5NO2). Calculate the weight % of nitrobenzene in thevapour.

16. The vapour pressure of a certain liquid is given by the equation:

Log10P = 3.54595 T

7.313+ 1.40655 log10 T where P is the vapour pressure in mm and T = Kelvin Temperature.

Determine the molar latent heat of vaporisation as a function of temperature. Calculate the its value at 80 K.

17. If the apparent degree of ionization of KCl (KCl =74.5 gm mol�1) in water at 290 K is 0.86. Calculate the massof KCl which must be made up to 1 dm3 of aqueous solution to the same osmotic pressure as the 4.0%solution of glucose at that temperature.

18. An ideal solution was prepared by dissolving some amount of cane sugar (nonvolatile) in 0.9 moles ofwater. The solution was then cooled just below its freezing temperature (271 K), where some ice getseparated out. The remaining aqueous solution registered a vapour pressure of 700 torr at 373 K. Calculatethe mass of ice separated out, if the molar heat of fusion of water is 6 kJ.

19. The freezing point of 0.02 mol fraction solution of acetic acid (A) in benzene (B) is 277.4K. Acetic acid existspartly as a dimer 2A = A2. Calculate equilibrium constant for the dimerisation. Freezing point of benzene is278.4 K and its heat of fusion Hf is 10.042 kJ mol1.



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20. The vapour pressure of two pure liquids, A and B that form an ideal solution are 300 and 800 torr respectively,at temperature T. A mixture of the vapour of A and B for which the mole fraction of A is 0.25 is slowlycompressed at temperature T. Calculate(a) the composition of the first drop of the condensate,(b) the total pressure when this drop is formed,(c) the composition of the solution whose normal boiling point is T,(d) the pressure when only the last bubble of vapour remains, and(e) the composition of the last bubble.

21. (a) A liquid mixture of benzene and toluene is composed of 1 mol of benzene and 1 mol of toluene. If thepressure over the mixture at 300 K is reduced, at what pressure does the first bubble form?

(b) What is the composition of the first bubble formed.(c) If the pressure is reduced further, at what pressure does the last trace of liquid disappear?(d) What is the composition of the last drop of liquid?(e) What will be the pressure, composition of the liquid and the composition of vapour, when 1 mol of the

mixture has been vaporized? Given PT0 = 40 mm Hg, PB

0 = 100 mm Hg

PART - I : IIT-JEE PROBLEMS (PREVIOUS YEARS)

* Marked Questions are having more than one correct option.

1. To 500 cm3 of water, 3.0 × 10�3 kg of acetic acid is added. If 23% of acetic acid is dissociated, what willbe the depression in freezing point? kf and density of water are 1.86 K kg�1 and 0.997 g cm�3 respectively:

[JEE 2000](A) 0.186 K (B) 0.228 K (C) 0.372 K (D) 0.556 K

2. An aqueous solution of 6.3 g oxalic acid dihydrate is made up to 250 mL. The volume of 0.1 N NaOHrequired to completely neutralise 10 mL of this solution is : [JEE 2001](A) 40 mL (B) 20 mL (C) 10 mL (D) 4 mL.

3. The vapour pressure of two miscible liquids (A) and (B) are 300 and 500 mm of Hg respectively. In a flask 10mole of (A) is mixed with 12 mole of (B). However, as soon as (B) is added, (A) starts polymerising into acompletely insoluble solid. The polymerisation follows first-order kinetics. After 100 minute, 0.525 mole of asolute is dissolved which arrests the polymerisation completely. The final vapour pressure of the solution is400 mm of Hg. Estimate the rate constant of the polymerisation reaction. Assume negligible volume changeon mixing and polymerisation and ideal behaviour for the final solution. [JEE 2001]

4. During depression of freezing point in a solution, the following are in equilibrium : [JEE 2003](A) Liquid solvent-solid solvent (B) Liquid solvent-solid solute(B) Liquid solute-solid solute (D) Liquid solute-solid solvent

5. Match the boiling point with Kb for x, y and z, if molecular weight of x, y and z are same. [JEE 2003]b.pt. Kb

x 100 0.68y 27 0.53z 253 0.98

6. A 0.004 M solution of Na2SO4 is isotonic with a 0.010 M solution of glucose at same temperature. Theapparent degree of dissociation of Na2SO4 is(A) 25% (B) 50% (C) 75% (D) 85% [JEE 2004]

7. 1.22 g of benzoic acid is dissolved in (i) 100 g acetone (Kb for acetone = 1.7) and (ii)100 g benzene



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(Kb for benzene = 2.6). The elevation in boiling points Tb is 0.17°C and 0.13°C respectively.

(a) What are the molecular weights of benzoic acid in both the solutions?(b) What do you deduce out of it in terms of structure of benzoic acid? [JEE 2004]

8. The elevation in boiling point of a solution of 13.44 g of CuCl2 in 1kg of water using the followinginformation will be (Molecular weight of CuCl2 = 134.4 and Kb = 0.52 K molal�1) : [JEE 2005](A) 0.16 (B) 0.05 (C) 0.1 (D) 0.2

9. 72.5 g of phenol is dissolved in 1 kg of a solvent (kf = 14) which leads to dimerization of phenol and freezingpoint is lowered by 7 kelvin. What percent of total phenol is present in dimeric form? [JEE 2006]

10. When 20 g of naphtholic acid (C11H8O2) is dissolved in 50 g of benzene (Kf = 1.72 K kg mol�1), a freezingpoint depression of 2 K is observed. The van�t Hoff factor (i) is(A) 0.5 (B) 1 (C) 2 (D) 3 [JEE 2007]

Paragraph for Question No. Q.11 to Q.13

Properties such as boiling point, freezing point and vapour pressure of a pure solvent change when solutemolecules are added to get homogeneous solution. These are called colligative properties. Applications ofcolligative properties are very useful in day-to-day life. One of its examples is the use of ethylene glycol andwater mixture as anti-freezing liquid in the radiator of automobiles.

A solution M is prepared by mixing ethanol and water. The mole fraction of ethanol in the mixture is 0.9.

Given : Freezing point depression constant of water waterfK = 1.86 K kg mol�1

Freezing point depression constant of ethanol ethanolfK = 2.0 K kg mol�1

Boiling point elevation constant of water waterbK = 0.52 K kg mol�1

Boiling point elevation constant of ethanol ethanolbK = 1.2 K kg mol�1

Standard freezing point of water = 273 KStandard freezing point of ethanol = 155.7 KStandard boiling point of water = 373 KStandard boiling point of ethanol = 351.5 KVapour pressure of pure water = 32.8 mm HgVapour pressure of pure ethanol = 40 mm HgMolecular weight of water = 18 g mol�1

Molecular weight of ethanol = 46 g mol�1

In answering the following questions, consider the solutions to be ideal dilute solutions and solutes to benon-volatile and non-dissociative.

11. The freezing point of the solution M is [JEE 2008](A) 268.7 K (B) 268.5 K (C) 234.2 K (D) 150.9 K

12. The vapour pressure of the solution M is [JEE 2008](A) 39.3 mm Hg (B) 36.0 mm Hg (C) 29.5 mm Hg (D) 28.8 mm Hg

13. Water is added to the solution M such that the mole fraction of water in the solution becomes 0.9. The boilingpoint of this solution is [JEE 2008](A) 380.4 K (B) 376.2 K (C) 375.5 K (D) 354.7 K

14. The Henry�s law constant for the solubility of N2 gas in water at 298 K is 1.0 × 105 atm. The mole fraction of



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N2 in air is 0.8. The number of moles of N2 from air dissolved in 10 moles of water at 298 K and 5 atm pressureis [JEE 2009](A) 4.0 × 10�4 (B) 4.0 × 10�5 (C) 5.0 × 10�4 (D) 4.0 × 10�5

15. The freezing point (in ºC) of a solution containing 0.1 g of K3[Fe(CN)6] (Mol. Wt. 329) in 100 g of water(Kf = 1.86 K kg mol�1) is : [JEE 2011](A) � 2.3 × 10�2 (B) � 5.7 × 10�2 (C) � 5.7 × 10�3 (D) � 1.2 × 10�2

16. For a dilute solution containing 2.5 g of a non-volatile non-electrolyte solute in 100 g of water, the elevation inboiling point at 1 atm pressure is 2ºC. Assuming concentration of solute is much lower than the concentration

of solvent, the vapour pressure (mm of Hg) of the solution is (taken Kb = 0.76 K kg mol�1) [JEE 2012](A) 724 (B) 740 (C) 736 (D) 718

PART - II : AIEEE PROBLEMS (PREVIOUS YEARS)

1. Which of the following concentration factor is affected by change in temperature ? [AIEEE-2002](1) Molarity (2) Molality (3) Mol fraction (4) Weight fraction

2. Freezing point of an aqueous solution is (�0.186)ºC. Elevation of boiling point of the same solution is

Kb = 0.512ºC, Kf = 1.86ºC, find the increase in boiling point. : [AIEEE 2002](1) 0.186 ºC (2) 0.0512 ºC (3) 0.092 ºC (4) 0.2372 ºC

3. In a mixture A and B components show negative deviation as : [AIEEE 2002](1) Vmix > 0(2) Vmix < 0(3) A�B interaction is weaker than A�A and B�B interaction

(4) None of the above reasons is correct.

4. In a 0.2 molal aqueous solution of a weak acid HX, the degree of ionization is 0.3. Taking kf for water as1.85, the freezing point of the solution will be nearest to : [AIEEE 2003](1) � 0.480 ºC (2) � 0.360 ºC (3) � 0.260 ºC (4) + 0.480 ºC

5. 25 ml of a solution of barium hydroxide on titration with a 0.1 molar solution of hydrochloric acid gavea litre value of 35 ml. The molarity of barium hydroxide solution was : [AIEEE 2003](1) 0.07 (2) 0.14 (3) 0.28 (4) 0.35

6. A pressure cooker reduces cooking time for food because � [AIEEE-2003](1) The higher pressure inside the cooker crushes the food material(2) Cooking involves chemical changes helped by a rise in temperature(3) Heat is more evenly distributed in the cooking space(4) Boiling point of water involved in cooking is increased

8. If liquids A and B form an ideal solution, the [AIEEE 2003](1) enthalpy of mixing is zero(2) entropy of mixing is zero(3) free energy of mixing is zero(4) free energy as well as the entropy of mixing are each zero.

9. Which one of the following aqueous solutions will exhibit highest boiling point ? [AIEEE 2004](1) 0.01 M Na2SO4 (2) 0.01 M KNO3 (3) 0.015 M urea (4) 0.015 M glucose

10. 6.02 × 1020 molecules of urea are present in 100 ml of its solution. The concentration of urea solutionis : [AIEEE 2004](1) 0.001 M (2) 0.01 M (3) 0.02 M (4) 0.1 M.

11. To neutralise completely 20 mL of 0.1 M aqueous solution of phosphorus acid (H3PO3), the volume of0.1 M aqueous KOH solution required is : [AIEEE 2004](1) 10 mL (2) 20 mL (3) 40 mL (4) 60 mL



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12. Which of the following liquid pairs shows a positive deviation from Raoult�s law ? [AIEEE 2004](1) water � hydrochloric acid (2) benzene - methanol(C) water � nitric acid (4) acetone � chloroform

13. Which one of the following statements is false ? [AIEEE 2004](1) Raoult�s law states that the vapour pressure of a component over a solution is proportional to its

mole fraction.(2) The osmotic pressure () of a solution is given by the equation = MRT, where M is the molarity of

the solution.(3) The correct order of osmotic pressure for 0.01 M aqueous solutionof each compound is

BaCl2 > KCl > CH3COOH > sucrose.(4) Two sucrose solutions of same molality prepared in different solvents will have the same freezing

point depression.

14. If is the degree of dissociation of Na2SO4, the vant Hoff�s factor (i) used for calculating the moecular

mass is : [AIEEE 2005](1) 1 + (2) 1 � (3) 1 + 2 (4) 1 � 2.

15. Benzene and toluene form nearly ideal solutions. At 20ºC, the vapour pressure of benzene is 75 torr

and that of toluene is 22 torr. The partial vapour pressure of benzene at 20 ºC for a solution containing

78 g of benzene and 46 g of toluene in torr is : [AIEEE 2005](1) 50 (2) 25 (3) 37.5 (4) 53.5

16. Two solutions of a substance (non electrolyte) are mixed in the following manner. 480 ml of 1.5 M firstsolution + 520 mL of 1.2 M second solution. What is the molarity of the final mixture ? [AIEEE 2005](1) 1.20 M (2) 1.50 M (3) 1.344 M (4) 2.70 M

17. Equimolar solutions in the same solvent have : [AIEEE 2005](1) same boiling point but different freezing point(2) same freezing point but different boiling point(3) same boiling and same freezing points(4) differnet boiling and freezing points

18. 18 g of glucose (C6H12O6) is added to 178.2 g of water. The vapour pressure of water for this aqueoussolution at 100º C is - [AIEEE 2006](1) 7.60 Torr (2) 76.00 Torr (3) 752.40 Torr (4) 759.00 Torr

19. Density of a 2.05 M solution of acetic acid in water is 1.02 g/mL. The molality of the solution is -[AIEEE 2006](1) 3.28 mol kg�1 (2) 2.28 mol kg�1 (3) 0.44 mol kg�1 (4) 1.14 mol kg�1

20. A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm at 300 K. The vapourpressure of propyl alcohol is 200 mm. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure(in mm) at the same temperature will be - [AIEEE 2007](1) 350 (2) 300 (3) 700 (4) 360

21. A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60 g mol�1)

in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 gcm�3, molar

mass of the substance will be - [AIEEE 2007]

(1) 90.0g mol�1 (2) 115.0g mol�1 (3) 105.0g mol�1 (4) 210.0 g mol�1

22. The density (in g mL�1) of a 3.60 M sulphuric acid solution that is 29% H2SO4 (Molar mass = 98 g mol�1)

by mass will be - [AIEEE 2007]

(1) 1.64 (2) 1.88 (3) 1.22 (4) 1.45



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23. The vapour pressure of water at 20º C is 17.5 mm Hg. If 18g of glucose (C6H12O6) is added to 178.2 g of water

at 20° C, the vapour pressure of the resulting solution will be - [AIEEE 2008]

(1) 15.750 mm Hg (2) 16.500 mm Hg (3) 17.325 mm Hg (4) 17.675 mm Hg

24. At 80º C , the vapour pressure of pure liquid �A� is 520 mm Hg and that of pure liquid �B� is 1000 mm Hg. If a

mixture solution of �A� and �B� boils at 80º C and 1 atm pressure, the amount of �A� in the mixture is (1 atm =

760 mm Hg) [AIEEE 2008]

(1) 34 mol percent (2) 48 mol percent (3) 50 mol percent (4) 52 mol percent

25. A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements

is correct regarding the behaviour of the solution ? [AIEEE 2009]

(1) The solution is non-ideal, showing +ve deviation form Raoult�s Law

(2) The solution is non-ideal, showing �ve deviation from Raoult�s Law

(3) n-heptane shows +ve deviation while ethanol shows � ve deviation from Raoult�s Law

(4) The solution formed is an ideal solution

26. Two liquids X and Y form an ideal solution At 300 K, vapour pressure of the solution containing 1 mol of X and

3 mol of Y is 550 mmHg. At the same temperature, if 1 mol of Y is further added to this solution, vapour

pressure of the solution increases by 10 mmHg. Vapour pressure (in mmHg) of X and Y in their pure states

will be, respectively - [AIEEE 2009]

(1) 300 and 400 (2) 400 and 600 (3) 500 and 600 (4) 200 and 300

27. If sodium sulphate is consisered to be completely dissociated into cations and anions in aqueous solution,

the change in freezing point of water (Tf), when 0.01 mole of sodium sulphate is dissolved in 1 kg of water,

is (Kf = 1.86 K kg mol�1) [AIEEE 2010]

(1) 0.0372 K (2) 0.0558 K (3) 0.0744 K (4) 0.0186 K

28. On mixing, heptane and octane form an ideal solution. At 373 K, the vapour pressure of the two liquid

components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution

obtained by mixing 25.0 g of heptane and 35 g of octane will be (molar mass of heptane � 100 g mol�1 and of

octane = 114 g mol�1) [AIEEE 2010]

(1) 72.0 kPa (2) 36.1 kPa (3) 96.2 kPa (4) 144.5 kPa

29. Kf for water is 1.86 K kg mol�1. if your automobile radiator holds 1.0 kg of water, how many grams of ethylene

glycol (C2H6O2) must you add to get the freezing point of the solution lowered to � 2.8ºC? [AIEEE 2012]

(1) 72 g (2) 93 g (3) 39 g (4) 27 g

NCERT QUESTIONS

1. The partial pressure of ethane over a solution containing 6.56 × 10�3 g of ethane is 1 bar. If the solutioncontains 5.00 × 10�2 g of ethane, then what shall be the partial pressure of the gas ?

2. An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of thesolvent. What is the molar mass of the solute ?



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3. Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and35g of octane ?

4. Calculate the mass of a non-volatile solute (molar mass 40 g mol�1) which should be dissolved in 114 goctane to reduce its vapour pressure to 80%.

5. A solution containing 30g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at298 K. Calculate :(i) molar mass of the solute (ii) vapour pressure of water at 298 K.

6. A 5% solution (by mass) of cane sugar in water has freezing point of 271 K. Calculate the freezing point of5% glucose in water if freezing point of pure water is 273.15 K.

7. Two elements A and B form compounds having formula AB2 and AB4. When dissolved in 20 g of benzene(C6H6), 1 g of AB2 lowers the freezing point by 2.3 K whereas 1.0 g of AB4 lowers it by 1.3 K. The molardepression constant for benzene is 5.1 K kg mol�1. Calculate atomic masses of A and B.

8. At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmoticpressure of the solution is 1.52 bars at the same temperature, what would be its concentration ?

9. Henry's law constant for the molality of methane is benzene at 298 K is 4.27 × 105 mm Hg. Calculate thesolubility of methane in benzene at 298 K under 760 mm Hg.

10. 100 g of liquid A (molar mass 140 g mol�1) was dissolved in 1000 g of liquid B (molar mass 180 g mol�1). Thevapour pressure of pure liquid B was found to be 500 torr. Calculate the vapour pressure of pure liquid A andits vapour pressure in the solution if the total vapour pressure of the solution is 475 Torr.

11. Benzene and toluene form ideal solution over the entire range of composition. The vapour pressure of purebenzene and toluene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively. Calculate the mole fractionto benzene in vapour phase if 80 g of benzene is mixed with 100 g of toluene.

12. The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximateproportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm.At 298 K if the Henry's law constants for oxygen and nitrogen at 298 K are 3.30 107 mm and 6.51 107 mmrespectively, calculate the composition of these gases in water.

13. Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litre of water at25 C, assuming that it is completely dissociated.

14. Methanol and ethanol form nearly and ideal solution at 300 K. A solution is made by mixing 32 g methanoland 23 g ethanol. Calculate the partial pressures of its constituents and total vapour pressure of the solutionat 300 K. (P°CH3OH = 90 mm Jg ; P°C2H5OH = 51 mm Hg)

15. Vapour pressures of pure benzene and toluene at 293 K is 75 mm Hg and 22 mm Hg respectively. 23.4 g ofbenzene and 64.4 g of toluene are mixed. If the two form and ideal solution, calculate the mole fraction ofbenzene in the vapour phase assuming that the vapours are in equilibrium with the liquid mixture at thistemperature.

16. The boiling point of water becomes 100.52°C if 1.5 g of a non-volatile solute is dissolved in 100 mL of it.

Calculate the molecular mass of the solute. (Kb for water = 0.6 K m�1)

17. On dissolving 0.25 g of a non-volatile substance in 30 mL benzene (density = 0.8 mL�1), its freezing pointdecreases by 0.40°C. Calculate the molecular mass of the substance (Kf = 5.12 K kg mol�1)

18. Osmotic pressure of a solution contaning 7 g of a protein per 100 mL of a solution is 25 mm Hg at 37°C.

Calculate molar mass of the protein.



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19. The osmotic pressure of a dilute aqueous solution of compound (X) containing 0.12 g per litre is twice theosmotic pressure of a dilute aqueous solution of another compound (Y) containing 0.18 g per litre. What isthe ratio of molecular mass of (X) to that of (Y) ? Both (X) and (Y) remain in molecular form in solution.

20. 1 litre aqueous solution of sucrose (molar mass = 342) weighing 1015 g is found oto record an osmoticpressure of 4.82 atm at 293 K. What is the molality of the sucrose solution ?(R = 0.0821 litre atm K�1 mol�1)

21. Assuming complete ionisation, calculate the expected freezing point of solution prepared by dissolving 6 g ofGlauber's salt, Na2SO4.10H2O in 0.1 kg of H2O. (Kf for H2O = 1.86 K kg mol�1)

22. Calculate the van't Hoff factor of CdSO4 (mol. mass = 208.4) if the dissociation of 5.21 g of CdSO4 in half litrewater gives a depression in freezing point of 0.168°C. (Kf for water = 1.86 kg mol�1)

23. How much urea (molar mass = 60 g mol�1) should be dissolved in 50 g of water so that its vapour pressure atroom temperature is reduced by 25% ? Calculate molality of the solution obtained.



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# 31

Exercise # 1PART-I

A-1. (B) A-2. (D) A-3. (B) A-4. (C) A-5. (B) A-6. (A) A-7. (A)

A-8. (B) B-1. (D) B-2. (D) B-3. (D) B-4. (A) B-5. (C) B-6. (D)

B-7. (D) B-8. (A) B-9. (C) B-10. (D) B-11. (B) B-12. (B) B-13. (C)

B-14. (C) B-15. (B) B-16. (B) C-1. (C) C-2. (A) C-3. (C) C-4. (B)

C-5. (B) C-6. (C) C-8. (B) C-9. (C) C-10. (A) C-11. (B)

C-12. (C) C-13. (D) C-14. (B) C-15. (B) C-16. (B) D-1. (B) D-2. (C)

D-3. (D) D-4. (D) D-5. (B) D-6. (A) D-7. (A) D-8. (C) D-9. (C)

D-10. (B) D-11. (A) D-12. (A) D-13. (D) D-14. (D) D-15. (C)

D-16.* (ABCD) D-17. (B) E-1. (B) E-2. (C) E-3. (A) E-4. (D) E-5. (C)

E-6. (B) E-7. (C) E-8. (A) E-9. (D) E-10. (A) E-11.* (BD) E-12. (A)

E-13. (B) E-14.* (B*D) E-15. (A) F-1. (B) F-2. (C) F-3. (B) F-4. (A)

F-5. (D) F-6. (B) F-7. (A) F-8. (B) F-9. (C) F-10. (A) F-11. (B)

G-1. (C) G-2. (D) G-3. (D) G-4. (B) G-5. (D) G-6. (A) G-7. (C)

G-8. (A) G-9. (B) G-10. (D) G-11. (A) G-12. (D) G-13. (B) G-14. (C)

H-1. (D) H-2. (A) H-3. (A) H-4. (D) H-5. (B) H-6. (A) H-7. (A)

H-8. (A) H-9. (C) H-10. (D) H-11. (A) H-12. (C) H-13. (C) H-14. (A)

H-15. (B) I-1. (C) I-2. (B) I-3. (D) I-4.* (AC) I-5. (B)

I-6.* (ABCD)

PART-II1. (B) 2. (A) 3. (B) 4. (B) 5. (D) 6. (A) 7. (B)

8. (D) 9. (A) 10. (C) 11. (A) 12. (A) 13. (D) 14. (B)

15. (C) 16. (A) q (B) p (C) r

Exercise # 2PART-I

1. (D) 2. (D) 3. (A) 4. (A) 5. (B) 6. (A) 7. (A)

8. (B) 9. (B) 10. (A) 11. (C) 12. (C) 13. (C) 14. (A)

15. (C) 16. (A) 17. (C) 18. (D) 19. (B) 20. (A) 21. (D)

22. (A) 23. (C) 24. (A) 25. (A) 26. (A) 27. (D) 28. (B)

29. (C) 30. (C) 31. (C) 32. (C) 33. (A) 34. (C) 35. (D)

36. (B) 37. (D) 38. (C) 39. (D) 40. (D) 41. (C) 42. (D)

43. (A) 44. (C) 45. (B) 46. (B) 47. (B) 48. (A) 49. (B)



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# 32

PART-II

1. C44H88O44 2. 746.24 mm/Hg

3. (a) 3.79°C, (b) 0.018, (c) 4.65 atm, (d) 251.5 4. (a) 210.65, (b) 62.35%

5. Tb = 102.3oC 6. Tf = -0.73oC 7. 0.73

8. xb = 0.2472, Yb = 0.4473 9. 46.33°C 10. xa" = 0.1 11. a = 0.7333

12. �19.91°C, 7.63 M 13. M = 53.8 14. 0.93 15. 20.11 %

16. Hv at 80 K is 1659.1 calorie; Hv = R [2.303 × 313.7 + 1.40655T

17. 8.9 gm 18. 12.54 19. K = 3.36

20. (a) 0.47, (b) 565 torr, (c) xA=0.08, xB= 0.92, (d) 675 torr, (e) x'A= 0.11, x'B= 0.89

21. (a) 70 mm Hg (b) YA = 2/7, YB = 5/7 (c) P = 400/7 = 57.14 mm (d) A B

5 2X ,X

7 7

(e) 63.25 mm (liquid composition 0.3875, 0.6125) (vapour composition 0.6125, 0.3875)

Exercise # 3PART-I

1. (A) 2. (C) 3. 1.0 × 10�4 4. (A)

5. Kb(x) = 0.68, Kb(y) = 0.53, Kb(z) = 0.98 6. (C)

7. (a) 122,(b) It means that benzoic acid remains as it is in acetone while it dimerises in benzene as

C

O H O

C O H O

8. (A) 9. 35% phenol is present in dimeric form 10. (A) 11. (D)

12. (B) 13. (B) 14. (A) 15. (A) 16. (A)

PART-II

1. (1) 2. (2) 3. (2) 4. (1) 5. (2) 6. (4) 8. (1)

9. (1) 10. (2) 11. (3) 12. (2) 13. (4) 14. (3) 15. (1)

16. (3) 17. (3) 18. (3) 19. (2) 20. (1) 21. (4) 22. (3)

23. (3) 24. (3) 25. (1) 26. (3) 27. (2) 28. (1) 29. (2)

Exercise # 4NCERT

14. PCH3OH = 60 mm Hg ; P°C2H5OH = 17 mm Hg ; Total vapour pressure = 77 mm Hg

15. 0.59 16. 100.28°C 17. 133.33 18. 54094 19. m1 : m2 : : 1 :3

20. 0.2112 m 21. 271.95 K 22. 1.806

23. Mass of urea = 55.56 g ; molality of solution = 18.52



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