Solution and Colligative Properties Exercise # 1

SOLUTION AND COLLIGATIVE PROPERTIES Exercise # 1 [Single Correct Choice Type Questions] 1. We have 100 mL of 0.1 M KCl solution. To make it 0.2 M, (A) evaporate 50 mL water (B) evaporate 50 mL solution (C) add 0.1 mol KCl (D) add 0.01 mol KCl 2. Persons are medically considered to have lead poisoning if they have a concentration greater than 10 micrograms of lead per decilitre of blood. Concentration in parts per billion is : (A) 1000 (B) 100 (C) 10 (D) 1 3. Which of the following concentration factors can be calculated if the mole fraction and density of an aqueous solution of HCl are known ? (A) Molality (B) Molarity (C) Percent by mass (D) Normality 4. Which statement best explains the meaning of the phrase “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 5. 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 6. The vapour pressure of water depends upon : (A) Surface area of container (C) Temperature (B) Volume of container (D) All 7. A liquid is kept in a closed vessel. If a glass plate (negligible mass) with a small hole is kept on top of the liquid 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 8. 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. 9. Among the following substances, the lowest vapour pressure is exerted by : (A) Water (B) Mercury (C) Kerosene (D) Rectified spirit 10. When a liquid that is immiscible with water was steam distilled at 952ºC at a total pressure of 748 torr, the distillate contained 1.25 g of the liquid per gram of water. The vapour pressure of water is 648 torr at 95.2ºC, what is the molar mass of liquid? (A) 7.975 g/mol (B) 166 g/mol (C) 145.8 g/mol (D) None of these 11. Two liquids X and Y are perfectly immiscible. If X and Y have molecular masses in ratio 1 : 2, the total vapour pressure of a mixture of X and Y prepared in weight ratio 2 : 3 should be (Px0 = 400 torr, Py0 = 200 torr) (A) 600 torr (B) 400 torr (C) 800 torr (D) 1000 torr 12. An ideal solution contains two volatile liquids A (pº = 100 torr) and B (pº = 200 torr). If mixture contain 1 mole of A and 4 mole of B then total vapour pressure of the distillate is: (A) 150 (B) 180 (C) 188.88 (D) 198.88 13.. The vapour pressure of two pure liquids A and B, that form an ideal solution are 100 and 900 torr respectively at temperature T. This liquid solution of A and B is composed of 1 mole of A and 1 mole of B. What will be the pressure, when 1 mole of mixture has been vaporized ? (A) 800 torr (B) 500 torr (C) 300 torr (D) None of these 14. For a binary ideal liquid solution, the total pressure of the solution is given as : (A) Ptotal = PºA + (PºA – PºB) XB (B) Ptotal = PºB + (PºA – PºB) XA (C) Ptotal = PºB + (PºB – PºA) XA (D) Ptotal = PºB + (PºB – PºA) XB 15. Given at 350 K pA° = 300 torr and pB° = 800 torr, the composition of the mixture having a normal boiling point of 350 K is (A) XA = 0.08 (B) XA = 0.06 (C) XA = 0.04 (D) XA = 0.02 16. Two liquids A and B have PºA and PºB in the ratio of 1 : 3 and the ratio of number of moles of A and B in liquid phase are 1 : 3 then mole fraction of ‘A’ in vapour phase in equilibrium with the solution is equal to : (A) 0.1 (B) 0.2 (C) 0.5 (D) 1.0 17. Which of the following will form non-ideal solution ? (A) C2H5OH and water (B) HNO3 and water (C) CHCl3 and CH3COCH3 (D) C6H6 and C6H5CH3 18. 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 19. A solution of sulphuric acid in water exhibits : (A) Negative deviations from Raoult’s law (C) Ideal properties 20. (B) Positive deviations from Raoult’s law (D) The applicability of Henry’s law For chloroform and acetone or for a solution of chloroform and acetone if ps (observed (actual)) is compared with ps (Theoretical (Raoult)) then which of the following is /are true ? (A) ps(actual) < ps(raoult) (C) Limit X acetone  0 (pºchloroform – ps(actual))= 0 (B) Limit X chloroform  0 (pºacetone – ps actual) = 0 (D) pºacetone > pº chloroform near room temperature 21. 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. 22. Consider a binary mixture of volatile liquids. If at XA = 0.4 the vapour pressure of solution is 580 torr then the mixture could be (pAº = 300 torr, pB° = 800 torr) : (A) CHCl3 – CH3COCH3 (B) C6H5 Cl – C6 H5 Br (C) C6H6 – C6 H5 CH3 (D) nC6H14 – n C7H16 23. The solubility of N 2(g) in water exposed to the atmosphere, when the partial pressure is 593 mm is 5.3 × 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 SOLUTION AND COLLIGATIVE PROPERTIES 24. 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 25. Select correct statements : (A) Gases which have high value of Van der Waals 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 . 26. Some of the following gases are soluble in water due to formation of their ions : I : CO2 ; II : NH3 ; III : HCl ; IV : CH4 ; V : H2 Water insoluble gases can be : (A) I, IV , V (B) I, V (C) I, II, III (D) IV, V 27. In which of the following pairs of solutions will the values of the vant Hoff 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)2SO4. 6H2O (C) 0.20 M NaCl and 0.10 M BaCl2 (D) 0.05 M FeSO4 (NH4)2SO4 . 6H2O and 0.02 M KCl . MgCl2 . 6H2O 28. One mole of a solute A is dissolved in a given volume of solvent. The association of the solute take place as follows: An nA If  is the degree of association of A, the van’t Hoff factor i is expressed as: (A) i  1 –  (B) i  1   n (C) i = 1– α + 1 α n (D) i = 1 29. If Mnormal is the normal molecular mass and  is the degree of ionization of K3[Fe(CN)6], then the abnormal molecular mass of the complex in the solution will be : (A) Mnormal (1 + 2)–1 (B) Mnormal (1 + 3)–1 (C) Mnormal (1 + )–1 (D) equal to Mnormal 30. The vapour pressure of a solution of a non-volatile solute B in a solvent A is 95% of the vapour pressure of the solvent at the same temperature. If the molecular weight of the solvent is 0.3 times the molecular weight of the solute, what is the ratio of weight of solvent to solute. (A) 0.15 (B) 5.7 (C) 0.2 (D) none of these 31. If P0 and P are the vapour pressures of a solvent and its solution respectively and N1 and N2 are the mole fractions of the solvent and non-volatile solute respectively, then correct relation is : (A) P = P0N2 (B) P = P0N1 (C) P0 = PN1 (D) P = P0(N1/N2) 32. A complex of iron and cyanide ions is 100% ionised at 1m (molal). If its elevation in b.p. is 2.08. Then the complex is (Kb = 0.52° mol–1 kg) : (A) K3[Fe(CN)6] (B) Fe(CN)2 (C) K4[Fe(CN)6] (D) Fe(CN)4 33. A solution of x moles of sucrose in 100 grams of water freezes at 0.20C. As ice separates the freezing point goes down to 0.250C. How many grams of ice would have separated? (A) 18 grams (B) 20 grams (C) 25 grams (D) 23 grams 34. Sea water is found to contain 5.85 % NaCl and 9.50% MgCl2 by weight of solution. Calculate its normal boiling point assuming 80% ionisation for NaCl and 50% ionisation of MgCl2 (Kb(H2O) = 0.51 kgmol–1 K). (A) Tb = 101.9°C (B) Tb = 104.9°C (C) Tb = 108.5°C (D) Tb = 110.3°C 35. PtCl4 . 6H2O can exist as a hydrated complex 1 molal aq. solution has depression in freezing point of 3.72°. 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 36. How many moles of sucrose should be dissolved in 500 gms of water so as to get a solution which has a difference of 104°C between boiling point and freezing point. (Kf = 1.86 K Kg mol–1, Kb = 0.52 K Kg mol–1) (A) 1.68 (B) 3.36 (C) 8.40 (D) 0.840 37. Which of the following has been arranged in order of decreasing freezing point? (A) 0.05 M KNO3 > 0.04 M CaCl2 > 0.140 M sugar > 0.075 M CuSO4 (B) 0.04 M BaCl2 > 0.140 M sucrose > 0.075 M CuSO4 > 0.05 M KNO3 (C) 0.075 M CuSO4 > 0.140 M sucrose > 0.04 M BaCl2 > 0.05 M KNO3 (D) 0.075 M CuSO4 > 0.05 M NaNO3 > 0.140 M sucrose > 0.04 M BaCl2 38. 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) I is hypertonic (C) II is hypotonic (D) none is correct 39. Select correct statement : (A) Osmosis, like all colligative properties, results from an increase in entropy as pure solvent passes through the membrane and mixes with the solution (B) Desalination of sea-water is done by reverse osmosis (C) Both are correct statements (D) None is correct statement 40. Osmotic pressure of 30% solution of glucose is 1.20 atm and that of 3.42% solution of cane sugar is 2.5 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. 41. 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 solventsolvent interactions. 42. A sample of air is saturated with benzene (vapor pressure = 100 mm Hg at 298 K), 750mm Hg pressure. 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 43. 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 of its initial volume (assume temperature is constant). (A) 8.77 mmHg (B) 17.54 mmHg (C) 35.08 mmHg (D) between 8.77 and 17.54 mmHg Water vapour Liquid water SOLUTION AND COLLIGATIVE PROPERTIES 44. All of the water in a 0.20 M solution of NaCl was evaporated and a 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 45. A 20.0 mL sample of CuSO4 solution was evaporated to dryness, leaving 0.967 g of residue. What was the molarity of the original solution ? (Cu = 63.5) (A) 48.4 M (B) 0.0207 M (C) 0.0484 M (D) 0.303 M 46. When KCl dissolves in water (assume endothermic dissolution), then : (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 47. Water and chlorobenzene are immiscible liquids. Their mixture boils at 89ºC under a reduced pressure of 7.7 × 104 Pa. The vapour pressure of pure water at 89ºC is 7 × 104 Pa. Weight per cent of chlorobenzene in the distillate is: (A) 50 (B) 60 (C) 78.3 (D) 38.46 48. If two liquids A (PºA =100 torr) and B (PºB = 200 torr) are completely immiscible with each other, each one will behave independently of the other, are present in a closed vessel. The total vapour pressure of the system will be: (A) less than 100 torr (B) greater than 200 torr (C) between 100 to 200 torr (D) 300 torr 49. The vapor pressures of benzene, toluene and a xylene are 75 Torr, 22 Torr and 10 Torr respectively at 20ºC. Which of the following is not a possible value of the vapor pressure of an equimolar binary/ternary solution of these at 20ºC ? Assume all form ideal solution with each other. 2 1 1 (A) 48 (B) 16 (C) 35 (D) 53 2 3 2 50. Assuming the formation of an ideal solution, determine the boiling point of a mixture containing 1560 g benzene (molar mass = 78) and 1125 g chlorobenzene (molar mass = 112.5) using the following against an external pressure of 1000 Torr. (A) 90ºC (B) 100ºC (C) 110º (D) 120ºC 1800 Vapour 1350 Pressure 1000 540 400 300 200 chlorobenzene 90 100 110 120 t(cº) 800 600 400 200 0 (B) 0.2 0.4 0.6 0.8 1.0 Mole Fraction 0 (C) 0.2 0.4 0.6 0.8 1.0 Mole Fraction 0 (D) 0.2 0.4 0.6 0.8 1.0 Mole Fraction Boiling Point (A) 0.2 0.4 0.6 0.8 1.0 Mole Fraction Boiling Point 0 Boiling Point Pressure (mm Hg) Given P-x curve for a non-ideal liquid mixture (Fig.). Identify the correct T-x curve for the same mixture. Boiling Point 51. benzene 2200 0 0.2 0.4 0.6 0.8 1.0 Mole Fraction 52. If vapour pressures of pure liquids ‘A’ & ‘B’ are 300 and 800 torr respectively at 25°C. When these two liquids are mixed at this temperature to form a solution in which mole percentage of ‘B’ is 92, then the total vapour pressure is observed to be 0.95 atm. Which of the following is true for this solution. (A) Vmix > 0 (B) Hmix < 0 (C) Vmix = 0 (D) Hmix = 0 53. At 323 K, the vapour pressure in millimeters of mercury of a methanol-ethanol solution is represented by the pA equation p = 120 XA + 140, where XA is the mole fraction of methanol. Then the value of xlim is : A 1 X A (A) 250 mm (B) 140 mm (C) 260 mm (D) 20 mm 54. 1 1 Consider two liquids A & B having pure vapour pressures PA° & PB° forming an ideal solution. The plot of X v/s Y (where A A XA and YA are the mole fraction of liquid A in liquid and vapour phase respectively) is linear with slope and Y intercepts respectively : PAº (PAº – PBº ) and PBº PBº (PAº – PBº ) and PBº (A) P º B (C) P º A 55. 56. PAº (PBº – PAº ) and PBº PBº (PBº – PAº ) and PBº (B) P º B (D) P º A Which of the following is less than zero for ideal solutions ? (A) Hmix (B) Vmix (C) Gmix (D) Smix Which of the following curves represents the Henry’s law ? log m log m (A) log m (B) log P log m (C) (D) log P log P log P 57. According to Henry’s law, the solubility of a gas in a given volume of liquid increases with increase in : (A) Temperature (B) Pressure (C) Both (A) and (B) (D) None of these 58. The degree of dissociation of an electrolyte is  and its van’t Hoff factor is i. The number of ions obtained by complete dissociation of 1 molecule of the electrolyte is: (A) 59. i + α –1 α (B) i – α – 1 (C) Dry air is slowly passed through three solutions of different concentrations, c1, c2 and c3 ; each containing (non volatile) NaCl as solute and water as solvent, as shown in the Fig. If the vessel 2 gains weight and the vessel 3 loses weight, then : (A) c1 > c2 (B) c1 < c2 (C) c1 < c3 (D) c2 > c3 i –1 α (D) Vessel-1 i +1+ α 1– α Vessel-2 Vessel-3 SOLUTION AND COLLIGATIVE PROPERTIES 60. 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 61. A solute’S’ undergoes a reversible trimerization when dissolved in a certain solvent. The boiling point elevation of its 0.1 molal solution was found to be identical to the boiling point elevation in case of a 0.08 molal solution of a solute which neither undergoes association nor dissociation. To what percent had the solute ‘S’ undergone trimerization? (A) 30% (B) 40% (C) 50% (D) 60% 62. Barium ions, CN¯ and Co2+ form an ionic complex. If that complex is supposed to be 75% ionised in water with vant Hoff factor ‘ i ’ equal to four, then the coordination number of Co2+ in the complex can be : (A) Six (B) Five (C) Four (D) Six and Four both 63. Relative decrease in vapour pressure of an aqueous solution containing 2 moles [Cu(NH3)3 Cl] Cl in 3 moles H2O is 0.50. On reaction with AgNO3, this solution will form(assuming no change in degree of ionisation of substance on adding AgNO3) (A) 1 mol AgCl (B) 0.25 mol AgCl (C) 0.5 mol AgCl (D) 0.40 mol AgCl 64. In the following aqueous solutions (A) 1 m sucrose (B) 1 m potassium ferricyanide (C) 1 m potassium sulphate maximum value of vapour pressure of solution is that of : (A) A (B) B (C) C (D) equal 65. When only a little quantity of HgCl2(s) is added to excess KI(aq) to obtain a clear solution, which of the following is true for this solution? (no volume change on mixing) (A) Its boiling and freezing points remain same (B) Its boiling point is lowered (C) Its vapour pressure become lower (D) Its boiling point is raised (E) Its freezing point is lowered. 66. The freezing point of aqueous solution that contains 3% urea, 7.45% KCl and 9% of glucose is (given K f of water = 1.86 and assume molarity = molality). (A) 290 K (B) 285.5 K (C) 267.42 K (D) 250 K 67. x mole of KCI and y mole of BaCl2 are both dissolved in 1 kg of water. Given that x + y = 0.1 and Kf for water is 1.85 K/molal, what is the observed range of Tf, if the ratio of x to y is varied ? (A) 0.370 to 0.505º (B) 0.1850 to 0.930 (C) 0.560 to 0.930 (D) 0.370 to 0.930 68. Two beakers, one containing 20 ml of a 0.05 M aqueous solution of a non volatile, non electrolyte and the other, the same volume of 0.03 M aqueous solution of NaCl, are placed side by side in a closed enclose. What are the volumes in the two beakers when equation is attached ? Volume of the solution in 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 22.9 mL 69. Osmotic pressure of blood is 7.40 atm at 27°C. Number of moles of glucose to be used per litre 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 70. For a solution of 0.849 g of mercurous chloride in 50 g of HgCl2() the freezing point depression is 1.24ºC. Kf for HgCl2 is 34.3. What is the state of mercurous chloride in HgCl2 ? (Hg – 200, Cl – 35.5) (A) as Hg2Cl2 molecules (B) as HgCl molecules (C) as Hg+ and Cl– ions (D) as Hg22+ and Cl– ions 71. 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 72. 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 73. 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 74. Colligative properties have many practical uses, some of them may be : I : Melting of snow by salt II : Desalination of sea water III : Determination of molar mass IV : Determination of melting point and boiling point of solvent Actual practical uses are : (A) I, II (B) III, IV (C) I, II, III P Side Y Side X Q (D) II, III, IV 75. Select correct statement(s) : (A) When solid CaCl2 is added to liquid water, the boiling temperature rises (B) When solid CaCl2 is added to ice at 0°C, the freezing temperature falls (C) Both (A) and (B) (D) None of the above 76. The concentration of pollutant in ppm (w/w), that has been measured at 450 mg per 150 kg of sample is : (A) 3 ppm (B) 6 ppm (C) 3000 ppm (D) 330 ppm 77. Available are 1L of 0.1 M NaCl and 2L of 0.2 M CaCl2 solutions. Using only these two solutions what maximum volume of a solution can be prepared having [Cl–] = 0.34 M exactly. Both electrolytes are strong (A) 2.5 L (B) 2.4 L C) 2.3 L (D) None of these 78. Mole fraction of C3H5(OH)3 in a solution of 36 g of water and 46 g of glycerine is : (A) 0.46 (B) 0.36 (C) 0.20 (D) 0.40 79. 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] 80. In which case, van’t Hoff factor i remains unchanged ? [Assume common complexes of these ions] (A) PtCl4 reacts with KCl (B) aq. ZnCl2 reacts with aq. NH3 (C) aq. FeCl3 reacts with aq. K4[Fe(CN)]6 (D) KMnO4 reduced to MnO2 in alkaline medium (MnO2 a black ppt) 81. If pKa = – log Ka = 4, and Ka = Cx2 then Van’t Hoff factor for weak monobasic acid when C = 0.01 M is : (A) 1.01 (B) 1.02 (C) 1.10 (D) 1.20 144 SOLUTION AND COLLIGATIVE PROPERTIES 82. What is the normal boiling point of the solution represented by the phase diagram ? 1 atm P,atm nt lve So A B C D T°C (A) A (B) B (C) C (D) D 83. Select correct statement ? (A) Heats of vaporisation for a pure solvent and for a solution are similar because similar intermolecular forces between solvent molecules must be overcome in both cases (B) Entropy change between solution and vapour is smaller than the entropy change between pure solvent and vapour (C) Boiling point of the solution is larger than that of the pure solvent (D) All are correct statements 84. Ratio of Tb / Kb of 6% AB2 and 9% A2B (AB2 and A2B both are non-electrolytes) is 1 mol/kg in both cases. Hence, atomic masses of A and B are respectively : (A) 60, 90 (B) 40, 40 (C) 40, 10 (D) 10, 40 Consider following terms (m = molality) : 85. I : mKb ; II : mKbi III : ΔTb i Terms which can be expressed in degree (temperature) are (A) III, IV (B) I, II (C) I, II, IIII IV : Kb (D) I, III 86. Elevation in b.p. of an aqueous urea solution is 0.52°. (Kb = 0.52° mol–1 kg) Hence, mole-fraction of urea in this solution is : (A) 0.982 (B) 0.567 (C) 0.943 (D) 0.018 87. Insulin (C2H10O5)n is dissolved in a suitable solvent and the osmotic pressure  of the solution of various concentration (in kg/m3) is measured at 20ºC. The slope of a plot of  against c is found to be 8.134 × 10–3 (SI units) The molecular weight of the insulin (in kg/mol) is : (A) 4.8 × 105 (B) 9 × 105 (C) 293 × 103 (D) 8.314 × 105 88. An aqueous solution of a solute AB has b.p. of 101.08°C (AB is 100% ionised at boiling point of the solution) and freezes at – 1.80°C. Hence, AB (Kb / Kf = 0.3) (A) is 100% ionised at the f.p. of the solution (B) behaves as non-electrolyte at the f.p. of the solution (C) forms dimer (D) none of the above 89. Density of 1M solution of a non-electrolyte C6H12O6 is 1.18 g/mL. If Kf (H2O) is 1.86° mol–1 kg, solution freezes at : (A) – 1.58°C (B) – 1.86°C (C) – 3.16°C (D) 1.86°C 90. Mole fraction of a non-electrolyte in aqueous solution is 0.07. If Kf is 1.86° mol–1 kg, depression in f.p., Tf, is: (A) 0.26° (B) 1.86° (C) 0.13° (D) 7.78° 91. Total vapour pressure of mixture of 1 mol of volatile component A (pA° = 100 mmHg) and 3 mol of volatile component B (pB° = 60 mmHg) is 75 mm. For such case : (A) there is positive deviation from Raoult’s low (B) boiling point has been lowered (C) force of attraction between A and B is smaller than that between A and A or between B and B (D) all the above statements are correct 92. Water and chlorobenzene are immiscible liquids. Their mixture boils at 90°C under a reduced pressure of 7.82 × 104 Pa. The vapour pressure of pure water at 90°C is 7.03 × 104 Pa. On weight percent basis, chlorobenzene in the distillate is equal to (mol. wt. of chlorobenzene is 112.5 g mol–1) (A) 50 (B) 60 (C) 70 (D) 80 93. Relative decrease in vapour pressure of an aqueous NaCl is 0.167. Number of moles of NaCl present in 180g of H2O is (A) 2 mol (B) 1 mol (C) 3 mol (D) 4 mol 94. What is the normal freezing point of the solution represented by the phase diagram ? t v en So l n u tio Sol P,atm So T0 lid T1 T2 T3 T,°C (A) T1 (B) T2 (C) T3 (D) T0 95. Select correct statement : (A) Solution has more molecular randomness than a pure solvent has, the entropy change between solution and solid is larger than the entropy change between pure solvent and solid (B) Heats of fusion of solution and solvent are similar since similar forces of intermolecular forces are involved (C) Sugar containing solution freezes at a lower temperature than pure water (D) All are correct statements 96. Some entropy change are represented in figure. Select correct entropy change. Vapour Solution S4 S3 S2 Solvent S1 Solid (A) S1, S2, S3 (B) S1, S2, S4 (C) S1, S2, S3 , S4 (D) S2 and S4 97. Which statement comparing solutions with pure solvent is not correct (A) A solution containing a non-volatile solute has a lower vapour pressure than pure solvent (B) A solution containing a non-volatile solute has a lower boiling point than pure solvent (C) A solution containing a non-volatile solute has a lower freezing point than pure solvent (D) A solution will have a greater mass than an equal volume of pure solvent if the solute has a molar mass greater than the solvent 98. A colligative property of a solution depends on the : (A) arrangement of atoms in solute molecule (B) total number of molecules of solute and solvent (C) number of molecules of solute in solution (D) mass of the solute molecules 99. Which has maximum freezing point ? (A) 6g urea solution in 100 g H2O (C) 6g sodium chloride in 100 g H2O (B) 6g acetic acid solution in 100g H2O (D) All have equal freezing point SOLUTION AND COLLIGATIVE PROPERTIES 100. Mole fraction of the toluene in the vapour phase which is in equilibrium with a solution of benzene (p° = 120 Torr) and toluene (p° = 80 Torr) having 2.0 mol of each is : (A) 0.50 (B) 0.25 (C) 0.60 (D) 0.40 101. The vapour pressure of pure benzene, C6H6 at 50°C is 268 Torr. How many moles of non-volatile solute per mol of benzene is required to prepare a solution of benzene having a vapour pressure of 167 Torr at 50°C ? (A) 0.377 (B) 0.605 (C) 0.623 (D) 0.395 102. An azeotropic solution of two liquids has a boiling point lower than either of them when it : (A) shows negative deviation from Raoult’s law (B) shows positive deviation from Raoult’s low (C) shows ideal behaviour (D) is saturated 103. Van’t Hoff factors of aqueous solutions of X, Y, Z are 1.8, 0.8 and 2.5. Hence, their (assume equal concentrations in all three cases) (A) b.p. : X < Y < Z (B) f. p. Z < X < Y (C) osmotic pressure : X = Y = Z (D) v. p. : Y < X < Z 104. Select correct statements : (A) The fundamental cause of all colligative properties is the higher entropy of the solution relative to that of the pure solvent (B) The freezing point of hydrofluoride solution is larger than that of equimolal hydrogen chloride solution (C) 1M glucose solution and 0.5 M NaCl solution are isotonic at a given temperature (D) All are correct statements 105. The vapour pressure of a pure liquid A is 40 mmHg at 310 K. The vapour pressure of this liquid in a solution with liquid B is 32 mmHg. Mole fraction of A in the solution, if it obeys Raoult’s law is : (A) 0.8 (B) 0.5 (C) 0.2 (D) 0.4 106. Depression of freezing point of 0.01 molal aq. CH3COOH solution is 0.02046°. 1 molal urea solution freezes at – 1.86°C. Assuming molality equal to molarity, pH of CH3COOH solution is : (A) 2 (B) 3 (C) 3.2 (D) 4.2 107. If relative decrease in vapour pressure is 0.4 for a solution containing 1 mol NaCl in 3 mol H2O, NaCl is .... % ionised. (A) 60% (B) 50% (C) 100% (D) 40% 108. Which of the following azeotropic solutions has the b.p. less than b.p. of the constituents A and B ? (A) CHCl3 and CH3COCH3 (B) CS2 and CH3COCH3 (C) CH3CH2OH and CH3COCH3 (D) CH3CHO and CS2 109. Vapour pressure of CCl4 at 25°C is 143 mmHg. 0.5 g of a non-volatile solute (molar mass = 65 mol–1) is dissolved in 100 mL of CCl4 (density = 1.538 g mL–1). Vapour pressure of solution is (A) 141.9 mmHg (B) 94.4 mmHg (C) 99.3 mmHg (D) 144.1 mmhg 110. A 0.50 molal solution of ethylene glycol in water is used as coolant in a car. If the freezing point constant of water is 1.86° per molal, at which temperature will the mixture freeze ? (A) 1.56°C (B) – 0.93°C (C) – 1.86°C (D) 0.93°C 111. The depression of freezing points of 0.05 molal aqueous solution of the following compounds are measured. 1. NaCl 2. K2SO4 3. C6H12O6 4. Al2(SO4)3 Which one of the above compounds will exhibit the maximum depression of freezing point ? (A) 3 (B) 2 (C) 4 (D) 1 112. The phase diagrams for the pure solvent (solid lines) and the solution (non-volatile solute, dashed line) are recorded below : P L (at 1 atm) O T The quantity indicated by L in the figure is : (A) p (B) Tf (C) Kbm (D) Kfm 113. The total concentration of dissolved particles inside red blood cells is approximately 0.30 M and the membrane surrounding the cells is semipermeable. What would be the osmotic pressure (in atmosphere) inside the cells become if the cells were removed from the blood plasma and placed in pure water at 298 K ? (A) 7.34 atm (B) 1.78 atm (C) 2.34 atm (D) 0.74 atm 114. The fundamental cause of T (depression is) : (A) higher entropy of the solution relative to that of pure solvent (B) lower entropy of the solution relative to that of pure solvent (C) higher enthalpy of the solution relative to that of pure solvent (D) lower enthalpy of the solution relative to that of pure solvent 115. Assuming each salt to be 90% dissociated which of the following will have highest osmotic pressure ? (A) Decimolar Al2 (SO4)3 (B) Decimolar BaCl2 (C) Decimolar Na2SO4 (D) A solution obtained by mixing equal volumes of (B) and (C) and filtering. 116. The boiling point of an azeotropic mixture of water and ethyl alcohol is less than that of theoretical value of water and alcohol mixture. Hence , the mixture shows : (A) That solution is highly saturated (B) Positive deviation from Raoult’s law (C) Negative deviation from Raoult’s law (D) Nothing can be said 117. On mixing 10 mL of acetone with 40 mL of chloroform , the total volume of the solution is : (A) < 50 mL (B) > 50 mL (C) = 50 mL (D) Cannot be predicted 118. For an ideal binary solution with PA0 / PB0 which relation between XA (mole fraction of A in liquid phase) and YA (mole fraction of A in vapour phase) is correct , XB and YB are mole fraction of B in liquid and vapour phase respectively: (Given : PA0 > PB0 ) (A) XA = YA (B) XA > YA XA YA (C) X < Y B B (D) XA, YA, XB and YB cannot be correlated 119. What will be the molecular weight of NaCl determined experimentally from elevation in the boiling point or depression in freezing point method ? (A) < 58.5 (B) > 58.5 (C) = 58.5 (D) None of these 120. Which characterises the weak intermolecular forces of attraction in a liquid ? (A) High boiling point (B) High vapour pressure (C) High critical temperature (D) High heat of vaporization SOLUTION AND COLLIGATIVE PROPERTIES 121. A teacher one day pointed out to his students the preculia fact that water is unique liquid which freezes exactly at 00 C and boils exactly at 1000 C. He asked the students to find the correct statement based on this fact : (A) Water dissolves anything however sparingly the dissolution may be (B) Water is a polar molecule (C) Boiling and freezing temperatures of water were used to define a temperature scale (D) Liquid water is denser than ice 122. When an ideal binary solution is in equilibrium with its vapour , molar ratio of the two components in the solution and in the vapour phase is : (A) Same (B) Different (C) May or may not be same depending upon volatile nature of the two components (D) None of the above The melting points of most of the solid substances increases with an increase of pressure acting on them. However, ice melts at a temperature lower than its usual melting point , when the pressure increases. This is because : (A) Ice is less denser than water (B) Pressure generates heat (C) The bonds break under pressure (D) Ice is not a true solid 123. 124. Which of the following liquid pairs shows a positive deviation from Raoult’s law ? (A) Acetone – chloroform (B) Benzene – methanol (C) Water – nitric acid (D) Water – hydrochloric acid 125. The relationship between osmotic pressure at 273 K when 10 g glucose (P1) ,10 g urea (P2) and 10 g sucrose (P3) are dissolved in 250 mL of water is : (A) P1 > P2 > P3 (B) P3 > P1 > P2 (C) P2 > P1 > P3 (D) P2 > P3 > P1 126. The amount of ice that will separate out on cooling a solution containing 50 g of ethylene glycol in 200 g water to – 9.30C is : (Kf= 1.86 K molality–1) (A) 38.71 g (B) 38.71 mg (C) 42 g (D) 42 mg 127. A liquid is in equilibrium with its vapours at its boiling point. On the average the molecules in the two phases have equal : (A) Potential energy (B) Total energy (C) Kinetic energy (D) Intermolecular forces 128. On the basis of intermolecular forces predict the correct order of decreasing boiling points of the compounds: (A) CH3OH > H2 > CH4 (B) CH3OH > CH4 > H2 (C) CH4 > CH3OH > H2 (D) H2 > CH4 > CH3OH 129. During depression of freezing point in a solution 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 EXERCISE - 1 1. A, B, D 2. B 3. A, B, C, D 4. B 5. B 6. C 7. B 8. B 9. B 10. C 11. A 12. C 24. C 13. C 14. B 15. A 16. A 25. A, C 26. D 27. B, D 17. A, B, C 18. A 19. A 20. A, B, C, D 21. C 22. A 23. B 28. C 29. B 30. B 31. B 32. A 33. B 34. A 35. C 36. D 37. A 38. A 39. C 40. C 41. A 42. C 43. B 44. C 45. D 46. C 49. D 50. B 51. B 52. B 53. C 54. B 55. C 56. A 57. B 58. A 59. B, D 61. A 62. B 63. C 64. A 65. B 66. C 67. A 68. B 69. A 70. A 71. A 72. D 73. C 74. C 87. C 75. C 88. B 76. A 89. B 77. A 90. D 78. C 91. D 79. B 92. C 80. B 93. B 81. C 94. A 82. D 95. D 83. D 96. C 84. C 97. B 85. C 98. C 86. D 99. A 100. D 101. A 102. B 47. D 48. D 60. C 103. B 104. D 105. A 106. B 107. C 108. C 109. A 110. B 111. C 112. C 113. A 114. A 115. A 116. B 117. A 118. C 119. A 120. B 121. C 122. C 123. A 124.B 126. A 127. C 128. B 129. A 125. C