Quiz: NCERT Class 12 Chemistry - Unit 2 (Solutions)

 

1. Which of the following is a colligative property?
a) Viscosity
b) Surface tension
c) Osmotic pressure
d) Density

2. The solubility of a gas in a liquid increases with:
a) Decrease in pressure and increase in temperature
b) Increase in pressure and decrease in temperature
c) Increase in pressure and increase in temperature
d) Decrease in pressure and temperature

3. The molarity of a solution is defined as:
a) Moles of solute per liter of solution
b) Moles of solute per kg of solvent
c) Grams of solute per liter of solution
d) Grams of solute per kg of solvent

4. Raoult’s law states that:
a) The partial vapor pressure of a component is directly proportional to its mole fraction in the solution.
b) The boiling point of a solution is inversely proportional to its molality.
c) The freezing point of a solution is directly proportional to its molarity.
d) The osmotic pressure is directly proportional to the molecular weight of the solute.

5. A solution containing 1 mole of non-volatile solute in 1 kg of solvent has a boiling point elevation constant (Kb) of 0.52 K kg/mol. What is the boiling point of the solution if the solvent’s boiling point is 100°C?
a) 100.52°C
b) 101.04°C
c) 99.48°C
d) 100.26°C

6. The van’t Hoff factor (i) for NaCl dissolved in water is approximately:
a) 1
b) 2
c) 3
d) 4

7. The depression in freezing point is observed because:
a) Solute particles increase the vapor pressure of the solvent.
b) Solute particles decrease the vapor pressure of the solvent.
c) Solute particles increase the freezing point of the solvent.
d) Solute particles decrease the boiling point of the solvent.

8. Which of the following shows a positive deviation from Raoult’s law?
a) Acetone and chloroform
b) Water and ethanol
c) Benzene and toluene
d) Ethanol and cyclohexane

9. Osmotic pressure of a solution is directly proportional to:
a) Temperature only
b) Volume only
c) Molarity and temperature
d) Molarity and volume

10. Two liquids form an azeotropic mixture. This means they:
a) Have no deviation from Raoult’s law
b) Have the same boiling points and composition in liquid and vapor phase
c) Can be separated completely by distillation
d) Have no interaction between their molecules

Answer Key

  1. c) Osmotic pressure
  2. b) Increase in pressure and decrease in temperature
  3. a) Moles of solute per liter of solution
  4. a) The partial vapor pressure of a component is directly proportional to its mole fraction in the solution.
  5. a) 100.52°C
  6. b) 2
  7. b) Solute particles decrease the vapor pressure of the solvent.
  8. d) Ethanol and cyclohexane
  9. c) Molarity and temperature
  10. b) Have the same boiling points and composition in liquid and vapor phase

Additional Quiz: NCERT Class 12 Chemistry - Unit 2 (Solutions)

1. Which of the following units is used for molality of a solution?
a) moles/L
b) moles/kg
c) moles/m³
d) moles/cm³

2. If two solutions have the same osmotic pressure at the same temperature, they are called:
a) Hypertonic
b) Hypotonic
c) Isotonic
d) Supersaturated

3. Henry’s law constant for a gas is 75 kPa/mol fraction75 \, \text{kPa/mol fraction}. What is the solubility of the gas in water at a pressure of 225 kPa225 \, \text{kPa}?
a) 1
b) 2
c) 3
d) 4

4. The boiling point of a solvent increases when a non-volatile solute is added because:
a) The vapor pressure of the solution is higher.
b) The vapor pressure of the solution is lower.
c) The solute increases the rate of evaporation.
d) The solute reduces the molecular interactions.

5. A solution is prepared by dissolving 0.6 g of urea (molar mass = 60 g/mol) in 90 g of water. Calculate the molality of the solution.
a) 0.01 m
b) 0.1 m
c) 1 m
d) 10 m

6. The freezing point depression constant (KfK_f) of water is 1.86 K kg/mol1.86 \, \text{K kg/mol}. What is the freezing point of a 1 m solution of a non-electrolyte in water?
a) 0°C
b) -1.86°C
c) -3.72°C
d) 1.86°C

7. Which of the following pairs of liquids form a negative deviation from Raoult’s law?
a) Benzene and toluene
b) Acetone and chloroform
c) Ethanol and cyclohexane
d) Water and ethanol

8. When 1 mol of solute is added to 1 kg of solvent, the boiling point of the solution is elevated by 0.52°C0.52°C. What is the molal boiling point elevation constant (KbK_b) of the solvent?
a) 0.26 K kg/mol0.26 \, \text{K kg/mol}
b) 0.52 K kg/mol0.52 \, \text{K kg/mol}
c) 1.04 K kg/mol1.04 \, \text{K kg/mol}
d) 2.08 K kg/mol2.08 \, \text{K kg/mol}

9. For a dilute solution, the relative lowering of vapor pressure is equal to:
a) Mole fraction of the solute
b) Mole fraction of the solvent
c) Molarity of the solute
d) Molality of the solvent

10. Which colligative property is most useful in determining the molar mass of large biomolecules like proteins?
a) Relative lowering of vapor pressure
b) Elevation in boiling point
c) Depression in freezing point
d) Osmotic pressure

Answer Key

  1. b) moles/kg
  2. c) Isotonic
  3. c) 3
  4. b) The vapor pressure of the solution is lower.
  5. b) 0.1 m
  6. b) -1.86°C
  7. b) Acetone and chloroform
  8. b) 0.52 K kg/mol0.52 \, \text{K kg/mol}
  9. a) Mole fraction of the solute
  10. d) Osmotic pressure

More Quiz: NCERT Class 12 Chemistry - Unit 2 (Solutions)

1. Which of the following factors affects the rate of dissolution of a solid in a liquid?
a) Temperature
b) Surface area of the solute
c) Stirring
d) All of the above

2. The unit of Henry’s law constant in the case of a gas dissolved in a liquid is:
a) atm/mol
b) atm/mol fraction
c) mol/L
d) mol/kg

3. What happens to the boiling point of a solvent when a non-volatile solute is added to it?
a) It decreases
b) It increases
c) It remains unchanged
d) It first increases and then decreases

4. The molality of a solution is independent of:
a) Temperature
b) Pressure
c) Volume of solution
d) Nature of solute

5. A solution of urea in water shows what kind of colligative properties?
a) Positive deviation
b) Negative deviation
c) No deviation
d) Normal deviation

6. Which of the following is true for an ideal solution?
a) The enthalpy of mixing is zero.
b) The vapor pressure of the solution is greater than that of the pure solvent.
c) The solution exhibits positive deviation from Raoult’s law.
d) The freezing point is raised upon adding a solute.

7. The osmotic pressure of a solution is directly proportional to:
a) Volume of solution
b) Temperature
c) Solute concentration
d) All of the above

8. Which of the following is a characteristic of the solution formed by ethanol and water?
a) It forms a positive deviation from Raoult’s law
b) It forms a negative deviation from Raoult’s law
c) It does not show any deviation from Raoult’s law
d) It does not form a solution at all

9. When 1 mol of a non-volatile solute is dissolved in 1000 g of a solvent, the depression in freezing point is 2°C. What is the molal freezing point depression constant (Kf) of the solvent?
a) 1 K kg/mol
b) 2 K kg/mol
c) 4 K kg/mol
d) 0.5 K kg/mol

10. If the vapor pressure of a solvent in a solution is 0.8 atm and the vapor pressure of the pure solvent is 1 atm, what is the mole fraction of the solute in the solution?
a) 0.2
b) 0.4
c) 0.8
d) 0.5

Answer Key

  1. d) All of the above
  2. b) atm/mol fraction
  3. b) It increases
  4. a) Temperature
  5. c) No deviation
  6. a) The enthalpy of mixing is zero.
  7. d) All of the above
  8. b) It forms a negative deviation from Raoult’s law
  9. b) 2 K kg/mol
  10. a) 0.2

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