solution and colligative properties (MCQ ,numerical type question) Class xii

1.Calculate the molality of a solution that contains 51.2 g of naphthalene, C10H8, in 500 mL of carbon tetrachloride. The density of CCl4 is 1.60 g/mL.

(a) 0.250 m

(b) 0.500 m

(c) 0.750 m

(d) 0.840 m

2. What is the molality of a solution labeled "8.6% glucose (C6H12O6) by weight?" (Note: If the question does not give the solvent, assume it is water.)

(a) 0.26 m

(b) 0.34 m

(c) 0.44 m

(d) 0.52 m

3. Calculate the mole fraction of C2H5OH in a solution that contains 46 grams of ethanol, C2H5OH, and 64 grams of methanol, CH3OH.

(a) 1/3

(b) 0.42

(c) 1/2

(d) 2/3

4. Which observation(s) reflect(s) colligative properties?

(I) A 0.5 m NaBr solution has a higher vapor pressure than a 0.5 m BaCl2 solution.

(II) A 0.5 m NaOH solution freezes at a lower temperature than pure water.

(III) Pure water freezes at a higher temperature than pure methanol.

(a) only I

(b) only II

(c) only III

(d) I and II

5. The vapor pressure of pure water at 85oC is 434 torr. What is the vapor pressure at 85 degree Celsius of a solution prepared from 100 mL of water (density 1.00 g/mL) and 150 g of diglyme, C6H14O3, a nonvolatile substance?

(a) 361 torr

(b) 390 torr

(c) 425 torr

(d) 388 torr

6.The vapor pressure of a solution containing a nonvolatile solute is directly proportional to the

(a) molality of the solvent.

(b) osmotic pressure of the solute.

(c) molarity of the solvent.

(d) mole fraction of solvent.

7. If 4.27 grams of sucrose, C12H22O11, are dissolved in 15.2 grams of water, what will be the boiling point of the resulting solution? (Kb for water = 0.512 oC/m) (Note: If the Kf and Kb are not given on the exam, you can find them on the back of the exam envelope.)

(a) 101.64  0C(degree Celsius)

(b) 100.42  0C

(c) 99.626  0C

(d) 100.73  0C

 8. What are the ideal van't Hoff factors for the following compounds:

Ba(OH)2, C6H12O6, K3PO4, HNO3 ?

(a) 1, 1, 1, 1

(b) 2, 1, 2, 2

(c) 3, 1, 4, 2

(d) 6, 3, 5, 5

9. Calculate the approximate initial boiling point (in oC) of a solution of 285 g of magnesium chloride in 2.0 kg of water. (Assume complete dissociation of the salt.)

(a) 103.1  0C (Degree Celsius)

(b) 101.6  0C

(c) 102.3  0C

(d) 100.8  0C

10. A solution made by dissolving 9.81 g of a nonvolatile nonelectrolyte in 90.0 g of water boiled at 100.37 oC at 760 mm Hg. What is the approximate molecular weight of the substance? (For water, Kb = 0.51 oC/m)

(a) 240 g/mol

(b) 150 g/mol

(c) 79 g/mol

(d) 61 g/mol

(e) 34 g/mol

11. What is the freezing point of an aqueous 1.00 m NaCl solution? (Kf = 1.86 oC/m) (Assume complete dissociation of the salt.)

(a) -1.86 0C (degree Celsius)

(b) +1.86 0C

(c) -3.72 0C

(d) -0.93 0C

12. A 17.3 mg sample of an organic compound (a non-electrolyte) was ground up with 420 mg of camphor to form a homogeneous mixture melting at 170.0 oC. What is the apparent formula weight of the organic compound? (Kf of camphor = 37.7 oC/m, m.p. of camphor = 178.4 oC) (Note: This is a freezing point depression problem - note the Kf of camphor - camphor is the solvent.)

(a) 353 g/mol

(b) 285 g/mol

(c) 231 g/mol

(d) 185 g/mol

13. Calculate the osmotic pressure associated with 50.0 g of an enzyme of molecular weight 98,000 g/mol dissolved in water to give 2600 mL of solution at 30.0 oC.

(a) 0.484 torr

(b) 1.68 torr

(c) 1.96 torr

(d) 3.71 torr

14. A 250 mL solution containing 21.4 g of a polymer in toluene had an osmotic pressure of 0.055 atm at 27 oC. What is the apparent formula weight of the polymer?

(a) 15,000 g/mol

(b) 18,000 g/mol

(c) 26,000 g/mol

(d) 38,000 g/mol

Class 10 Science chapter - 1 Chemical equations and reaction part -II

Q.1.Why should a magnesium ribbon be cleaned before burning in air?
Q.2  Write the balanced equation for the following chemical reactions.
 (i) Hydrogen + Chlorine → Hydrogen chloride
 (ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
 (iii) Sodium + Water → Sodium hydroxide + Hydrogen
Q.3.Write a balanced chemical equation with state symbols for the following reactions.
  (i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium   sulphate and the solution of sodium chloride.
  (ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Q.4  A solution of a substance ‘X’ is used for white washing.
  (i) Name the substance ‘X’ and write its formula.
  (ii) Write the reaction of the substance ‘X’ named in (i) above with water.
Q.5  Why is the amount of gas collected in one of the test tubes in Activity 1.7(hydrolysis of water) double of the amount collected in the other? Name this gas.
Q.6  Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Q.7  Identify the substances that are oxidised and the substances that are reduced in the following reactions.
       (i) 4Na(S)+O2(g)→2Na2O(S)
       (ii) CuO(S)+H2(g)→Cu(S)+H2O(l)

Solution and colligative properties (MCQ ,matching and reason assertion type question) with answer PART -1

Section - A   (MCQ) 

1.what does not change on changing temperatur -
(a).Mole fraction
(b).Molarity
(c).molality
(d).None of these
Ans- a,b

2.The magnitude colligative properties in all colloidal dispersion is . . . . than solution
(a). Lower 

(b). Higher 

(c) . Both 

(d). None
Ans- a

4. Equimolar solution in the same solvent have ( AIEEE 2005 )
(a).same boiling point but different-freezing point
(b). Same freezing print but different boiling (d). Different-boiling& different freezing point
(c).Same boiling and same freezing points
(d). Different boiling& different freezing points
Ans-c

5. which of the following is not a colligative property ? ( CPMT2001)
(a). optical activity
(b). Elevation in boiling point
(c). osmotic pressure
(d). lowering of vapour pressure
Ans- a

6. colligative properties of a solution depends upon _
(a). Nature of both solvent & solute
(b). The relative number of solute & solvent particles
(c).Nature of solute only
(d). Nature of solvent only
Ans -b

7.colligative properties are used for the determination of -
(a). Molar mass
(b). Equivalent weight
(c). Arrangement molecules
(d). melting & boiling point
(e). Both a & b
Ans-a 

8. Consider the three statements below. Which statement(s) is(are) true?
i. Hydration is a special case of solvation in which the solvent is water.
ii. The oxygen end of water molecules is attracted toward Ca2+ ions.
iii. The hydrogen end of water molecules is attracted toward Cl- ions.
(a) i only
(b) ii only
(c) iii only
(d) i and ii only
(e) i, ii, and iii
Ans-e 

9. Consider the following pairs of liquids. Which pairs are miscible?
1. benzene, C6H6, and hexane, C6H12
2. water and methanol, CH3OH
3. water and hexane
(a) 1, 2 only
(b) 2 only
(c) 1 only
(d) 1, 2, 3
(e) 2, 3 only
Ans- a

10.Which of the following units is useful in relating concentration of solution with its vapour pressure?
(a) mole fraction
(b) parts per million
(c) mass percentage
(d) molality
ans-a 11.On dissolving sugar in water at room temperature solution feels cool to touch.
Under which of the following cases dissolution of sugar will be most rapid?
(a) Sugar crystals in cold water.
(b) Sugar crystals in hot water.
(c) Powdered sugar in cold water.
(d) Powdered sugar in hot water.
Ans-d 12.At equilibrium the rate of dissolution of a solid solute in a volatile liquid solvent is ____________.
(a) less than the rate of crystallisation
(b) greater than the rate of crystallisation
(c) equal to the rate of crystallisation
(d) zero
ans-c 13. A beaker contains a solution of substance ‘A’. Precipitation of substance ‘A’ takes place when small amount of ‘A’ is added to the solution. The solution is _____________.
(a) saturated
(b) supersaturated
(c) unsaturated
(d) concentrated
ans- b
14.Maximum amount of a solid solute that can be dissolved in a specified amount of a given liquid solvent does not depend upon __________.
(a) Temperature
(b) Nature of solute
(c) Pressure
(d) Nature of solvent
ans- c
15.Low concentration of oxygen in the blood and tissues of people living at high altitude is due to _____________.
(a) low temperature
(b) low atmospheric pressure
(c) high atmospheric pressure
(d) both low temperature and high atmospheric pressure
ans- b
16.Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?
(a) Methanol and acetone.
(b) Chloroform and acetone.
(c) Nitric acid and water.
(d) Phenol and aniline.
ans- a
17.Colligative properties depend on .
(a) the nature of the solute particles dissolved in solution.
(b) the number of solute particles in solution.
(c) the physical properties of the solute particles dissolved in solution.
(d) the nature of solvent particles.
ans -b
18.Which of the following aqueous solutions should have the highest boiling point?
(a) 1.0 M NaOH
(b) 1.0 M Na2SO4
(c) 1.0 M NH4NO3
(d) 1.0 M KNO3
ans -b 
b.p. proportional to number of ions
19.The unit of ebulioscopic constant is _______.
(a) K kg mol–1 or K (molality)–1
(b) mol kg K–1 or K–1(molality)
(c) kg mol–1 K–1 or K–1(molality)–1
(d) K mol kg–1 or K (molality)
ans-a
20.In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl2 solution is _____.
(a) the same
(b) about twice
(c) about three times
(d) about six times
ans - a out of syllabus
21 An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because .
(a) it gains water due to osmosis.
(b) it loses water due to reverse osmosis.
(c) it gains water due to reverse osmosis.
(d) it loses water due to osmosis.
ans- d
22.At a given temperature, osmotic pressure of a concentrated solution of a substance .
(a) is higher than that at a dilute solution.
(b) is lower than that of a dilute solution.
(c) is same as that of a dilute solution.
(d) cannot be compared with osmotic pressure of dilute solution.
Ans-b
23.Which of the following statements is false?
(a) Two different solutions of sucrose of same molality prepared in different solvents will have the same depression in freezing point.
(b) The osmotic pressure of a solution is given by the equation Π = CRT ( where C is the molarity of the solution).
(c) Decreasing order of osmotic pressure for 0.01 M aqueous solutions of barium chloride, potassium chloride, acetic acid and sucrose is BaCl2 > KCl > CH3COOH > sucrose.
(d) According to Raoult’s law, the vapour pressure exerted by a volatile component of a solution is directly proportional to its mole fraction in the solution.
ans- a
24. The values of Van’t Hoff factors for KCl, NaCl and K2 SO4 , respectively, are_________.
(a) 2, 2 and 2
(b) 2, 2 and 3
(c) 1, 1 and 2
(d) 1, 1 and 1
ans-b out of syllabus
25. Which of the following statements is false?
(a) Units of atmospheric pressure and osmotic pressure are the same.
(b) In reverse osmosis, solvent molecules move through a semipermeable membrane from a region of lower concentration of solute to a region of higher concentration.
(c) The value of molal depression constant depends on nature of solvent.
(d) Relative lowering of vapour pressure, is a dimensionless quantity.
ans-b
26.Value of Henry’s constant KH___________ .
(a) increases with increase in temperature.
(b) decreases with increase in temperature.
(c) remains constant.
(d) first increases then decreases.
ans- a
27. The value of Henry’s constant KH is _______.
(a) greater for gases with higher solubility.
(b) greater for gases with lower solubility.
(c) constant for all gases.
(d) not related to the solubility of gases.

ans- b
29. We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentrations 0.1M, 0.01M and 0.001M, respectively. The value of van’t Hoff factor for these solutions will be in the order .
(a) iA < iB < iC
(b) iA > iB > iC
(c) iA = iB = iC
(d) iA < iB > iC
out of syllabus
30. On the basis of information given below mark the correct option.
Information:
(A) In bromoethane and chloroethane mixture intermolecular interactions of A–A and B–B type are nearly same as A–B type interactions.
(B) In ethanol and acetone mixture A–A or B–B type intermolecular interactions are stronger than A–B type interactions.
(C) In chloroform and acetone mixture A–A or B–B type intermolecular interactions are weaker than A–B type interactions.
(a) Solution (B) and (C) will follow Raoult’s law.
(b) Solution (A) will follow Raoult’s law.
(c) Solution (B) will show negative deviation from Raoult’s law.
(d) Solution (C) will show positive deviation from Raoult’s law.
ans -b 31. If two liquids A and B form minimum boiling azeotrope at some specific composition then .
(a) A–B interactions are stronger than those between A–A or B–B.
(b) vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution.
(c) vapour pressure of solution decreases because less number of molecules of only one of the liquids escape from the solution.
(d) A–B interactions are weaker than those between A–A or B–B.
ans-a 32. 4L of 0.02 M aqueous solution of NaCl was diluted by adding one litre of water. The molality of the resultant solution is .
(a) 0.004
(b) 0.008
(c) 0.012
(d) 0.016
Ans- d 33. On the basis of information given below mark the correct option.
Information : On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.
(a) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult’s law.
(b) At specific composition methanol-acetone mixture forms maximum boiling azeotrope and will show positive deviation from Raoult’s law.
(c) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show negative deviation from Raoult’s law.
(d) At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show negative deviation from Raoult’s law.
Ans-b

34. KH  value for Ar(g), CO2 (g), HCHO (g) and CH4 (g) are 40.39, 1.67, 1.83×10–5 and 0.413 respectively.
Arrange these gases in the order of their increasing solubility.
(a) HCHO < CH4 < CO2 < Ar
(b) HCHO < CO2 < CH4 < Ar
(c) Ar < CO2 < CH4 < HCHO
(d) Ar < CH4 < CO2 < HCHO
Ans-c

                                                   Section -B

Match the laws given in Column I with expresions given in Column II.

1. Match the terms given in Column I with expressions given in Column II.
   

          Assertion and Reason Type Questions

Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement. 
(d) Assertion and reason both are incorrect statements.
(e) Assertion is wrong statement but reason is correct statement.

1. Assertion : Molarity of a solution in liquid state changes with temperature.
   Reason : The volume of a solution changes with change in temperature.
2. Assertion : When methyl alcohol is added to water, boiling point of water increases.
   Reason : When a volatile solute is added to a volatile solvent elevation in boiling point is observed.
3. Assertion : When NaCl is added to water a depression in freezing point is observed.
   Reason : The lowering of vapour pressure of a solution causes depression in the freezing point.
4. Assertion : When a solution is separated from the pure solvent by a semi- permeable membrane, the solvent molecules pass through it from pure solvent side to the solution side.
   Reason : Diffusion of solvent occurs from a region of high concentration solution to a region of low concentration solution.                                           ans 1)-a  2)- c 3) i   4) b    

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