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#### UNIT TEST 9

11th Standard

Reg.No. :
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Chemistry

Time : 03:00:00 Hrs
Total Marks : 128

PART - A

30 x 1 = 30
1. The molality of a solution containing 1.8g of glucose dissolved in 250g of water is

(a)

0.2 M

(b)

0.01 M

(c)

0.02 M

(d)

0.04 M

2. Which of the following concentration terms is/are independent of temperature

(a)

molality

(b)

molarity

(c)

mole fraction

(d)

9a) and (c)

3. Stomach acid, a dilute solution of HCl can be neutralised by reaction with Aluminium hydroxide
Al (OH)3 + 3HCl (aq) → AlCl3 + 3 H2O
How many millilitres of 0.1 M Al(OH)3 solution are needed to neutralise 21 mL of 0.1 M HCl?

(a)

14 mL

(b)

7 mL

(c)

21 mL

(d)

none of these

4. The partial pressure of nitrogen in air is 0.76 atm and its Henry's law constant is 7.6 × 104 atm at 300K. What is the mole fraction of nitrogen gas in the solution obtained when air is bubbled through water at 300K?

(a)

1 x 10-4

(b)

1 x 10-6

(c)

2 x 10-5

(d)

1 x 10-5

5. The Henry's law constant for the solubility of Nitrogen gas in water at 350 K is 8 × 104 atm. The mole fraction of nitrogen in air is 0.5. The number of moles of Nitrogen from air dissolved in 10 moles of water at 350K and 4 atm pressure is

(a)

4 x 10-4

(b)

4 x 104

(c)

2 x 10-2

(d)

2.5 x 10-4

6. Which one of the following is incorrect for ideal solution?

(a)

$\Delta H_{mix}=0$

(b)

$\Delta U_{mix}=0$

(c)

$\Delta P=P_{observed}-P_{calculated\ by\ raoults\ law}=0$

(d)

$\Delta G_{mix}=0$

7. Which one of the following gases has the lowest value of Henry's law constant?

(a)

N2

(b)

He

(c)

CO2

(d)

H2

8. P1 and P2 are the vapour pressures of pure liquid components, 1 and 2 respectively of an ideal binary solution if x1 represents the mole fraction of component 1, the total pressure of the solution formed by 1 and 2 will be

(a)

P1 + x1 (P2 – P1)

(b)

P2 – x1 (P2 + P1)

(c)

P1 – x2 (P1 – P2)

(d)

P1 + x2 (P1 – P2)

9. Osometic pressure (p) of a solution is given by the relatio

(a)

$\pi$ = nRT

(b)

$\pi$V = nRT

(c)

$\pi$RT = n

(d)

none of these

10. Which one of the following binary liquid mixtures exhibits positive deviation from Raoults law?

(a)

Acetone + chloroform

(b)

Water + nitric acid

(c)

HCl + water

(d)

ethanol + water

11. The Henry's law constants for two gases A and B are x and y respectively. The ratio of mole fractions of A to B is 0.2. The ratio of mole fraction of B and A dissolved in water will be

(a)

${2x\over y}$

(b)

${y\over 0.2x}$

(c)

${0.2x\over y}$

(d)

${5x\over y}$

12. At 100C the vapour pressure of a solution containing 6.5g a solute in 100g water is 732mm. If Kb = 0.52, the boiling point of this solution will be

(a)

102oC

(b)

100oC

(c)

101oC

(d)

100.52oC

13. According to Raoults law, the relative lowering of vapour pressure for a solution is equal to

(a)

mole fraction of solvent

(b)

mole fraction of solute

(c)

number of moles of solute

(d)

number of moles of solvent

14. At same temperature, which pair of the following solutions are isotonic?

(a)

0.2 M BaCl2 and 0.2M urea

(b)

0.1 M glucose and 0.2 M urea

(c)

0.1 M NaCl and 0.1 M K2SO4

(d)

0.1 M Ba (NO3)2 and 0.1 M Na2 SO4

15. The empirical formula of a nonelectrolyte(X) is CH2O. A solution containing six gram of X exerts the same osmotic pressure as that of 0.025 M glucose solution at the same temperature. The molecular formula of X is

(a)

C2H4O2

(b)

C8H16O8

(c)

C4H8O4

(d)

CH2O

16. The KH for the solution of oxygen dissolved in water is 4 × 104 atm at a given temperature. If the partial pressure of oxygen in air is 0.4 atm, the mole fraction of oxygen in solution is

(a)

4.6 x 103

(b)

1.6 x 104

(c)

1 x 10-5

(d)

1 x 105

17. Normality of 1.25M sulphuric acid is

(a)

1.25 N

(b)

3.75 N

(c)

2.5 N

(d)

2.25 N

18. Two liquids X and Y on mixing gives a warm solution. The solution is

(a)

ideal

(b)

non-ideal and shows positive deviation from Raoults law

(c)

ideal and shows negative deviation from Raoults Law

(d)

non-ideal and shows negative deviation from Raoults Law

19. The relative lowering of vapour pressure of a sugar solution in water is 3.5 × 10–3. The mole fraction of water in that solution is

(a)

0.0035

(b)

0.35

(c)

0.0035/18

(d)

0.9965

20. The mass of a non-voltaile solute (molar mass 80 g mol–1) which should be dissolved in 92g of toluene to reduce its vapour pressure to 90%

(a)

10g

(b)

20g

(c)

9.2g

(d)

8.89g

21. For a solution, the plot of osmotic pressure (p) verses the concentration (c in mol L–1) gives a straight line with slope 310R where 'R' is the gas constant. The temperature at which osmotic pressure measured is

(a)

310 x 0.082 K

(b)

310oC

(c)

37oC

(d)

${310\over 0.082}K$

22. 200ml of an aqueous solution of a protein contains 1.26g of protein. At 300K, the osmotic pressure of this solution is found to be 2.52 × 10–3 bar. The molar mass of protein will be (R = 0.083 L bar mol–1 K–1)

(a)

62.22 Kg mol-1

(b)

12444 g mol-1

(c)

300 g mol-1

(d)

none of these

23. The Van't Hoff factor (i) for a dilute aqueous solution of the strong elecrolyte barium hydroxide is

(a)

0

(b)

1

(c)

2

(d)

3

24. What is the molality of a 10% W/W aqueous sodium hydroxide solution?

(a)

2.778

(b)

2.5

(c)

10

(d)

0.4

25. The correct equation for the degree of an associating solute, 'n' molecules of which undergoes association in solution, is

(a)

$\alpha={n(i-1)\over n-1}$

(b)

$\alpha^2={n(1-i)\over (n-1)}$

(c)

$\alpha={n(i-1)\over 1-n}$

(d)

$\alpha={n(1-i)\over n(1-i)}$

26. Which of the following aqueous solutions has the highest boiling point?

(a)

0.1 M KNO3

(b)

0.1 M Na3PO4

(c)

0.1 BaCl2

(d)

0.1 M K2SO4

27. The freezing point depression constant for water is 1.86o K Kg mol-1. If 5g Na2SO4 is dissolved in 45g water, the depression in freezing point is 3.64oC. The Vant Hoff factor for Na2SO4 is

(a)

2.50

(b)

2.63

(c)

3.64

(d)

5.50

28. Equimolal aqueous solutions of NaCl and KCl are prepared. If the freezing point of NaCl is –2oC, the freezing point of KCl solution is expected to be

(a)

-2oC

(b)

-4oC

(c)

-1oC

(d)

0oC

29. Phenol dimerises in benzene having van't Hoff factor 0.54. What is the degree of association?

(a)

0.46

(b)

92

(c)

46

(d)

0.92

30. Assertion: An ideal solution obeys Raoults Law
Reason: In an ideal solution, solvent-solvent, as well as solute-solute interactions, are similar to solute-solvent interactions.

(a)

both assertion and reason are true and reason is the correct explanation of assertion

(b)

both assertion and reason are true but reason is not the correct explanation of assertion

(c)

assertion is true but reason is false

(d)

both assertion and reason are false

31.     PART - B

18 x 2 = 36
32. The antiseptic solution of iodopovidone for the use of external application contains 10 % w/v of iodopovidone. Calculate the amount of iodopovidone present in a typical dose of 1.5 mL.

33. A litre of sea water weighing about 1.05 kg contains 5 mg of dissolved oxygen (O2). Express the concentration of dissolved oxygen in ppm.

34. How much volume of 6 M solution of NaOH is required to prepare 500 mL of 0.250 M NaOH solution.

35. Explain why the aquatic species are more comfortable in cold water during winter season rather than warm water during the summer.

36. At 400 K 1.5 g of an unknown substance is dissolved in solvent and the solution is made to 1.5 L. Its osmotic pressure is found to be 0.3 bar. Calculate the molar mass of the unknown substance.

37. Define (i) molality (ii) Normality.

38. What is a vapour pressure of liquid?
What is relative lowering of vapour pressure?

39. State and explain Henry’s law

40. State Raoult law and obtain expression for lowering of vapour pressure when nonvolatile solute is dissolved in solvent.

41. What is molal depression constant? Does it depend on nature of the solute?

42. What is osmosis?

43. Define the term ‘isotonic solution’.

44. You are provided with a solid ‘A’ and three solutions of A dissolved in water - one saturated, one unsaturated, and one super saturated. How would you determine which solution is which?

45. Explain the effect of pressure on the solubility.

46. A 0.25 M glucose solution at 370.28 K has approximately the pressure as blood does what is the osmotic pressure of blood?

47. Calculate the molality of a solution containing 7.5 g of glycine (NH2-CH2 -COOH) dissolved in 500 g of water.

48. Which solution has the lower freening point? 10 g of methanol (CH3OH) in 100g of water (or) 20 g of ethanol (C2H5OH) in 200 g of water.

49. How many moles of solute particles are present in one litre of 10-4 M potassium sulphate?

50. PART-  C

14 x 3 = 42
51. If 5.6 g of KOH is present in (a) 500 mL and (b) 1 litre of solution, calculate the molarity of each of these solutions.

52. 2.82 g of glucose is dissolved in 30 g of water. Calculate the mole fraction of glucose and water.

53. What volume of 4M HCl and 2M HCl should be mixed to get 500 mL of 2.5 M HCl?

54. Describe how would you prepare the following solution from pure solute and solvent
(a) 1 L of aqueous solution of 1.5 M CoCl2.
(b) 500 mL of 6.0% (V/V) aqueous methanol solution.

55. 0.24 g of a gas dissolves in 1 L of water at 1.5 atm pressure. Calculate the amount of dissolved gas when the pressure is raised to 6.0 atm at constant temperature.

56. Vapour pressure of a pure liquid A is 10.0 torr at 27°C. The vapour pressure is lowered to 9.0 torr on dissolving one gram of B in 20 g of A. If the molar mass of A is 200 then calculate the molar mass of B.

57. An aqueous solution of 2% nonvolatile solute exerts a pressure of 1.004 bar at the boiling point of the solvent. What is the molar mass of the solute when PA is 1.013 bar?

58. 0.75 g of an unknown substance is dissolved in 200 g water. If the elevation of boiling point is 0.15 K and molal elevation constant is 7.5 K Kg mol-1 then, calculate the molar mass of unknown substance

59. Ethylene glycol (C2H6O2) can be at used as an antifreeze in the radiator of a car. Calculate the temperature when ice will begin to separate from a mixture with 20 mass percent of glycol in water used in the car radiator. Kf for water = 1.86 K Kg mol-1 and molar mass of ethylene glycol is 62 g mol-1.

60. 2g of a non electrolyte solute dissolved in 75 g of benzene lowered the freezing point of benzene by 0.20 K. The freezing point depression constant of benzene is 5.12 K Kg mol-1. Find the molar mass of the solute.

61. What is the mass of glucose (C6 H12O6) in it one litre solution which is isotonic with 6 g L-1 of urea (NH2 CO NH2)?

62. The depression in freezing point is 0.24K obtained by dissolving 1g NaCl in 200g water. Calculate van’t-Hoff factor. The molal depression constant is 1.86 K Kg mol-1.

63. 0.2 m aqueous solution of KCl freezes at -0.68ºC calculate van’t Hoff factor. kf for water is 1.86 K kg mol-1.

64. The observed depression in freezing point of water for a particular solution is 0.093o C. Calculate the concentration of the solution in molality. Given that molal depression constant for water is 1.86 KKg mol-1.

65.   PART - D

6 x 5 = 30
66. Calculate the proportion of O2 and N2 dissolved in water at 298 K. When air containing 20% O2 and 80% N2 by volume is in equilibrium with it at 1 atm pressure. Henry’s law constants for two gases are KH(O2) = 4.6 x 104 atm and KH (N2) = 8.5 x 104 atm.

67. Calculate the mole fractions of benzene and naphthalene in the vapour phase when an ideal liquid solution is formed by mixing 128 g of naphthalene with 39 g of benzene. It is given that the vapour pressure of pure benzene is 50.71 mmHg and the vapour pressure of pure naphthalene is 32.06 mmHg at 300 K.

68. 2.56 g of Sulphur is dissolved in 100g of carbon disulphide. The solution boils at 319. 692 K. What is the molecular formula of Sulphur in solution The boiling point of CS2 is 319. 450K. Given that Kb for CS2 = 2.42 K Kg mol-1.

69. A sample of 12 M Concentrated hydrochloric acid has a density 1.2 gL–1 Calculate the molality

70. Henry’s law constant for solubility of methane in benzene is 4.2 x 10-5 mm Hg at a particular constant temperature At this temperature. Calculate the solubility of methane at i) 750 mm Hg ii) 840 mm Hg

71. The vapour pressure of pure benzene (C6H6) at a given temperature is 640 mm Hg. 2.2 g of non-volatile solute is added to 40 g of benzene. The vapour pressure of the solution is 600 mm Hg. Calculate the molar mass of the solute?