ChemistryFlame Institute

18. Which of the following can be measured by the ostwald-walker dynamic method

a. Vapour pressure of the solvent b. Relative lowering of vapour pressure c. Lowering of vapour pressure d. All of these Ans. b Explanation : Ostwald-Walker dynamic method is used for measurement of relative lowering of vapour pressure. (9)

17. Two liquids X and Y form an ideal solution. The mixture has a vapour pressure of 400 mm at 300 K when mixed in the molar ration of 1:1 and a vapour pressure of 350 mm when mixed in the molar ration of 1 : 2 at the same temperature. The vapour pressure of the two pur liquids X and Y respectively are

a. 250 mm, 550 mm b. 350 mm, 450 mm c. 350 mm, 700 mm d. 500 mm, 500 mm e. 550 mm, 250 mm Ans. e (11)

16. The vapour pressure of a solvent A is 0.08 atm when a non volatile substance B is added to this solvent its vapour pressure drops to 0.6 atm. What is mole fraction of B in solution

a. 0.25 b. 0.50 c. 0.75 d. 0.90 Ans. a (8)

15. The vapour pressure of a solvent decreased by 10mm of mercury, when a non volatile solute was added to the solvent. The mole fraction of the solute in the solutions is 0.2. What should be the mole fraction of the solvent, if decrease in the vapour pressure is to be 20mm of mercury

a. 0.8 b. 0.6 c. 0.4 d. 0.2 Ans. b (7)

14. In an experiment, 1 gof a non -volatile solute was dissolved in 100 g of acetone at 298 K. The vapour pressure of the solution was found to be 192.5 mmHg. The molecular weight of the solute is (vapour pressure of acetone = 195 mmHg)

a. 25.24 b. 35.24 c. 50 d. 55. 24 Ans. c (4)

13. 60g of Urea was dissolved in 9.9 moles, of water. if the vapour pressure of pure water is

Po , the vapour pressure of solution is a. 0.10 Po b. 1.10 Po c. 0.90 Po d. 0.99 Po Ans. c (7)

12. The vapour pressure of benzene at a certain temperature is 640 mm of Hg. A non volatile and non electrolyte solid weighing 2.175 g is added to 39.08 g of benzene. The vapour pressure of the solutions is 600 mm of Hg. What is the molecular weight of solid substance

a. 49.50 b. 59.6 c. 69.5 d. 79.8 Ans. c (37)

3.Two liquids X and Y form an ideal solution. At 300 K, vapour pressure of the solution containing 1 mole of X and 3 mol of Y is 550 mmHg. At the same temperature, if 1mol of Y is further added to this solution, vapour pressure of the solution increase by 10mmHg, Vapour pressure of X and Y in their pure states will be respectively

a. 200 and 300 b. 300 and 400 c. 400 and 600 d. 500 and 600 Ans. c (4)

2. Vapour pressure of chloroform and dichloromethane at

25° C are 200 mm Hg and 41.5mm Hg respectively. Vapour pressure of the solution obtained by mixing 25.5g of CHCl3 and 40g of CH2 Cl2 at the same temperature will be (Molecular mass of CHCl3 = 119.5u and molecular …

1. Vapour pressure of

CCl4 at 25° C is 143 mm of Hg. 0.5 g of a non-volatile solute is dissolved in 100 mL. CCl4 . Find the vapour pressure of the solution a. 141.93 mm b. 94.39 mm c. 199.34 mm d. 143.99 …

10. Liquid ‘M’ and liquid ‘N’ form an ideal solution. The vapour pressure of pure liquids ‘M’ and ‘N’ are 450 and 700 mmHg, respectively at the same temperature. Then correct statement is

( x M = Mole fraction of ‘M’ in solution; xN = Mole fraction of ‘N’ in solution; yM = Mole fraction of ‘M’ in vapour phase; yN = Mole fraction of ‘N’ in vapour phase) a. xM/xN < yM / yN b. (yM – yM ) …

8. Colligative properties are used for the determination of

a. Molar Mass b. Equivalent weight c. Arrangement of molecules d. Melting point and boiling point e. Both (a) and (b) Ans.a (6)

6. At 300 K, when a solute is added to a solvent its vapour pressure over the mercury reduces from 50 mm to 45 mm. The value of mole fraction of solute will be

a. 0.005 b. 0.010 c. 0.100 d. 0.900 Ans. c (13)

9. Whe n a substance is dissolved in a solvent, the vapour pressure of the solvent is decreased.. This results in

a. An increase in the boiling point of the solution b. a decrease in the boiling point of solvent c. The solution having a higher freezing point than the solvent d. The solution having a lower osmotic pressure than the …

5. A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290mm at 300 K. The vapour pressure of propyl is 0.6 it vapour pressure at the same temperature will be

a. 350 b. 300 c. 700 d. 360 Ans. a (9)

4. Which of the following aqueous solutions has the highest boiling point

a. 0.1 M KNO3 b. 0.1 M Na3 PO4 c. 0.1 M BaCl2 d. 0.1 M K2 SO4 Ans. b (37)

10. “Relative lowering in vapour pressure of solution containing non-volatile solute is directly proportional to mole fraction of solute”. Above statement is

a. Henry law b. Dulong and petit law c. Raoult’s law d. Le – Chatelier’s principle Ans. c (20)

63. NaClO solution reacts with

H2 SO 3 as, NaClO + H2SO 3 → NaCl + H2 SO4 . A solution of NaClO used in the above reaction contained 15 g of NaClO per litre. The normality of the solution would be a. 0.8 b. …

77. The molality of 90%

H2 SO4 solution is a. 1.8 b. 48.4 c. 91.83 d. 94.6 Ans. c (7)

2. Which of the following is a colligative property

a. Osmotic pressure b. Boiling point c. vapour pressure d. Freezing point Ans. a (14)

85. 4 L of 0.02 M aqueous solution of NaCl was diluted by adding 1 L of water. The molality of the resultant solution is

a. 0.004 b. 0.008 c. 0.012 d. 0.016 Ans. d (7)

84. Calculate the molality of a solution that contains 51.2g of nephthalene, in 500 mL of carbon tetrachloride. The density of

CCl4 of 1.60 g/ml a. 0.250 m b. 0.500 m c. 0.750 m d. 0.840 m e. 1.69 m Ans. b (10)

80. Density of a 2.05 M solution of acetic acid in water is 1.02 g/ml. The molality of the solution is

a. 1.14 mol kg -1 b. 3.28 mol kg -1 c. 2.28 mol kg -1 d.0.44 molkg -1 Ans. c (9)

79. Calculate the molaity of 1 litre solution of 93%

H 2 SO4 . The density of the solution is 1.84 g/ml a. 10.43 b. 20.36 c. 12.05 d. 14.05 Ans. a (5)

3. The colligative properties of a solution depend on

a. Nature of solute particles present in it b. Nature of solvent used c. Number of solute particles present in it d. Number of moles of solvent only Ans. c Explanation : Colligative properties of a solution not depend upon …

1. Equimola solutions in the same solvent have

a. Same boiling point but different freezing point b. Same freezing point but different boiling point c. Same boiling and same freezing points d. Different boiling and different freezing points Ans. c Explanation : Depression in freezing point and elevation …

98. The mole fraction of a solvent in aqueous solution of a solute is 0.8. The molality of the aqueous solutions is

a. 13.88 x 10 -3 b. 13.88 c. 13.88 x 10-2 d. 13.88 x 10-1 Ans. b (10)

97. 8g of NaOH is dissolved in 18 g of

H2 O. Mole fraction of NaOH in solution and molality of the solutions respectively are : a. 0.2, 11. 11 b. 0.167, 11. 11 c. 0.167, 22. 20 d. 0.2, 22.20 Ans. b (9)