COLLIGATIVE PROPERTIES
1. What are colligative properties?
A) Properties that depend on the type of solute particles
B) Properties that depend on the identity of the solvent
C) Properties that depend on the number of solute particles
in a solution
D) Properties that depend on the molecular weight of the
solute
Answer: C) Properties that depend on the number of solute
particles in a solution
7. Which colligative property is used in antifreeze to protect
car engines from freezing?
A) Boiling point elevation
B) Freezing point depression
C) Osmotic pressure
D) Vapor pressure lowering
Answer: B) Freezing point depression
8. The van't Hoff factor (i) represents:
A) Boiling point elevation
B) Freezing point depression
C) Osmotic pressure
D) Density
Answer: D) Density
A) The concentration of the solution
B) The number of solute particles in solution relative to the
number of formula units dissolved
C) The boiling point of the solution
D) The pressure exerted by the solute
Answer: B) The number of solute particles in solution
relative to the number of formula units dissolved
3. When a non-volatile solute is added to a solvent, what
happens to the vapor pressure of the solution?
9. A 1 molal solution of NaCl will have an effective
concentration of approximately:
A) It increases
B) It decreases
C) It remains the same
D) It first increases, then decreases
Answer: B) It decreases
A) 1 m
B) 2 m
C) 3 m
D) 0.5 m
Answer: B) 2 m
4. The decrease in vapor pressure due to the addition of a
solute is described by which law?
10. Why does adding salt to water lower its freezing point?
2. Which of the following is NOT a colligative property?
A) Henry’s Law
B) Raoult’s Law
C) Boyle’s Law
D) Charles’s Law
Answer: B) Raoult’s Law
5. The equation for boiling point elevation is:
A) ΔTb = Kb × m
B) ΔTf = Kf × m
C) Π = iMRT
D) P1 = X1 P0
Answer: A) ΔTb = Kb × m
6. The boiling point of a solution compared to the pure
solvent is:
A) Higher
B) Lower
C) The same
D) Unaffected
Answer: A) Higher
A) It increases the kinetic energy of water molecules
B) It disrupts the formation of the solid phase (ice)
C) It increases the vapor pressure
D) It decreases the temperature of water
Answer: B) It disrupts the formation of the solid phase (ice)
11. The equation for osmotic pressure is:
A) Π = iMRT
B) ΔTb = Kb × m
C) ΔTf = Kf × m
D) P = F/A
Answer: A) Π = iMRT
12. Which colligative property is used in reverse osmosis
water purification?
A) Freezing point depression
B) Boiling point elevation
C) Vapor pressure lowering
D) Osmotic pressure
Answer: D) Osmotic pressure
13. If two solutions of different concentrations are
separated by a semipermeable membrane, water will move
from:
A) The more concentrated solution to the less concentrated
solution
B) The less concentrated solution to the more concentrated
solution
C) Both solutions equally
D) Neither solution
Answer: B) The less concentrated solution to the more
concentrated solution
14. Which of the following solutes would have the greatest
effect on freezing point depression per mole?
A) Glucose
B) NaCl
C) MgCl₂
D) CH₄
Answer: C) MgCl₂
15. If a solute is non-volatile, how does it affect the vapor
pressure of a solution?
A) Increases it
B) Decreases it
C) No effect
D) First increases, then decreases
Answer: B) Decreases it
16. What is the primary cause of boiling point elevation?
A) Increased solute mass
B) Solute particles interfering with solvent evaporation
C) Increased solvent density
D) Solvent molecules bonding with the solute
Answer: B) Solute particles interfering with solvent
evaporation
17. Which factor does NOT affect the magnitude of
colligative properties?
A) The identity of the solute
B) The number of solute particles
C) The concentration of the solute
D) The van't Hoff factor
Answer: A) The identity of the solute
18. What happens to the boiling point when a solute is
added to water?
A) It decreases
B) It increases
C) It remains unchanged
D) It first increases, then decreases
Answer: B) It increases
19. If a solution has a lower freezing point than pure water,
what has likely been added?
A) A volatile solute
B) A non-volatile solute
C) A gas
D) A surfactant
Answer: B) A non-volatile solute
20. What happens to osmotic pressure when the
concentration of solute increases?
A) It increases
B) It decreases
C) It remains the same
D) It fluctuates
Answer: A) It increases
21. What is the unit of osmotic pressure?
A) Atmospheres (atm)
B) Molarity (M)
C) Molality (m)
D) Grams per liter (g/L)
Answer: A) Atmospheres (atm)
22. A solution is isotonic when:
A) It has more solute than another solution
B) It has less solute than another solution
C) It has the same osmotic pressure as another solution
D) It has a different vapor pressure
Answer: C) It has the same osmotic pressure as another
solution
23. In which application is osmotic pressure utilized?
A) Ice cream making
B) Reverse osmosis water purification
C) Fractional distillation
D) Electrolysis
Answer: B) Reverse osmosis water purification
24. Which of the following does NOT affect colligative
properties?
A) The nature of the solute
B) The number of solute particles
C) The concentration of the solution
D) The van't Hoff factor
Answer: A) The nature of the solute
25. Why does seawater have a lower freezing point than
freshwater?
A) It has a higher osmotic pressure
B) It contains dissolved salts that depress the freezing point
C) It has a lower vapor pressure
D) It is denser than freshwater
Answer: B) It contains dissolved salts that depress the
freezing point
26. What is the effect of increasing solute concentration on
boiling point?
A) No effect
B) Decreases it
C) Increases it
D) Causes temperature fluctuations
Answer: C) Increases it
27. Which type of solution has the highest osmotic
pressure?
A) Dilute solution
B) Concentrated solution
C) Pure solvent
D) Supersaturated solution
Answer: B) Concentrated solution
28. Colligative properties depend on:
A) The type of solute
B) The solvent's molecular weight
C) The number of solute particles
D) The temperature only
Answer: C) The number of solute particles
29. Why is salt spread on icy roads?
A) To lower the freezing point of water
B) To increase vapor pressure
C) To increase the freezing point
D) To evaporate water
Answer: A) To lower the freezing point of water
30. Which factor affects osmotic pressure the most?
A) Solvent polarity
B) Volume of the solution
C) Temperature and concentration of solute
D) Atmospheric pressure
Answer: C) Temperature and concentration of solute
Multiple Choice Questions on Colligative Properties (Set 2)
1. Which of the following is NOT affected by colligative
properties?
A) Boiling point
B) Freezing point
C) Molecular weight of solute
D) Osmotic pressure
Answer: C) Molecular weight of solute
2. Which statement best describes Raoult’s Law?
A) The boiling point of a solution increases when solute is
added.
B) The vapor pressure of a solvent decreases when a solute is
added.
C) The freezing point of a solution is higher than that of the
pure solvent.
D) The osmotic pressure of a solution is independent of
concentration.
Answer: B) The vapor pressure of a solvent decreases when
a solute is added.
3. If 1 mole of NaCl is dissolved in water, how many total
particles does it produce?
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
4. A solution has a freezing point of -5°C. What can be said
about this solution?
A) It contains a volatile solute.
B) It has a higher freezing point than pure water.
C) It is a pure solvent.
D) It contains a solute that lowers its freezing point.
Answer: D) It contains a solute that lowers its freezing point.
5. Why does a sugar solution have a higher boiling point
than pure water?
A) Sugar molecules absorb more heat.
B) Sugar increases the vapor pressure of water.
C) Sugar molecules interfere with solvent evaporation.
D) Sugar lowers the water temperature.
Answer: C) Sugar molecules interfere with solvent
evaporation.
6. If two solutions have the same concentration but one has
a higher van’t Hoff factor, which will have a lower freezing
point?
A) The solution with the higher van’t Hoff factor
B) The solution with the lower van’t Hoff factor
C) Both will have the same freezing point
D) Neither solution will freeze
Answer: A) The solution with the higher van’t Hoff factor
7. Which property is used to determine the molar mass of an
unknown solute?
A) Boiling point elevation
B) Freezing point depression
C) Osmotic pressure
D) All of the above
Answer: D) All of the above
8. What is the van’t Hoff factor for CaCl₂ in an ideal solution?
15. Reverse osmosis works by applying:
A) 1
B) 2
C) 3
D) 4
Answer: C) 3
A) Low pressure
B) High temperature
C) High pressure
D) Low temperature
Answer: C) High pressure
9. Which of the following solutions will have the highest
boiling point?
16. What is the effect of a solute on the boiling point of a
solution?
A) 1.0 M NaCl
B) 1.0 M K₂SO₄
C) 1.0 M C₆H₁₂O₆ (glucose)
D) 1.0 M CH₃COOH
Answer: B) 1.0 M K₂SO₄
A) It remains the same
B) It increases
C) It decreases
D) It fluctuates
Answer: B) It increases
10. Freezing point depression is directly proportional to:
17. Which of the following statements about colligative
properties is TRUE?
A) The type of solute
B) The van’t Hoff factor and molality
C) The temperature of the solution
D) The initial freezing point of the solvent
Answer: B) The van’t Hoff factor and molality
11. A 1.0 m aqueous solution of NaCl will freeze at
approximately:
A) 0°C
B) -1.86°C
C) -3.72°C
D) -5.58°C
Answer: C) -3.72°C
12. Why does adding a non-volatile solute decrease the
vapor pressure of a solution?
A) Solute particles replace solvent molecules at the surface.
B) Solute molecules evaporate faster than the solvent.
C) Solute molecules bond with solvent molecules
permanently.
D) Solute increases the volume of the solvent.
Answer: A) Solute particles replace solvent molecules at the
surface.
13. What is the primary factor affecting osmotic pressure?
A) Solvent density
B) Solute concentration
C) Type of solute
D) Solvent boiling point
Answer: B) Solute concentration
14. A hypertonic solution compared to a cell will cause:
A) No net water movement
B) Water to move into the cell
C) Water to move out of the cell
D) The cell to burst
Answer: C) Water to move out of the cell
A) They depend only on the identity of the solute.
B) They depend on the number of solute particles in solution.
C) They are affected by the color of the solution.
D) They do not change with concentration.
Answer: B) They depend on the number of solute particles in
solution.
18. Which of the following will have the greatest effect on
boiling point elevation?
A) 1.0 m NaCl
B) 1.0 m KCl
C) 1.0 m C₆H₁₂O₆ (glucose)
D) 1.0 m CaCl₂
Answer: D) 1.0 m CaCl₂
19. When a solution is hypotonic to a cell, what happens?
A) Water moves out of the cell
B) Water moves into the cell
C) The cell remains the same
D) The cell shrinks
Answer: B) Water moves into the cell
20. The formula for freezing point depression is:
A) ΔTb = Kb × m
B) ΔTf = Kf × m
C) Π = iMRT
D) P = F/A
Answer: B) ΔTf = Kf × m
21. Which factor does NOT affect boiling point elevation?
A) The number of solute particles
B) The type of solute
C) The van’t Hoff factor
D) The molality of the solution
Answer: B) The type of solute
22. What happens to the vapor pressure of a solution when
a non-volatile solute is added?
A) It increases
B) It decreases
C) It remains the same
D) It first increases, then decreases
Answer: B) It decreases
23. If a solution has an osmotic pressure of 5 atm, what will
happen if it is placed in a solution with an osmotic pressure
of 10 atm?
A) Water will enter the solution
B) Water will leave the solution
C) No water movement will occur
D) The solution will dissolve
Answer: B) Water will leave the solution
29. Freezing point depression is used in:
A) Boiling food
B) Road salt applications
C) Solar panels
D) Electrolysis
Answer: B) Road salt applications
30. Osmosis occurs due to differences in:
A) Temperature
B) Concentration
C) Pressure
D) Volume
Answer: B) Concentration
Basic Concept of Van’t Hoff Factor
1.
What does the Van’t Hoff factor (i) represent?
a) The number of ions a solute forms in solution
b) The freezing point of a solution
c) The boiling point of a solvent
d) The vapor pressure of a solvent
Answer: a) The number of ions a solute forms in
solution
2.
For a non-electrolyte in solution, what is the
expected Van’t Hoff factor (i)?
a) 0
b) 1
c) 2
d) More than 1
Answer: b) 1
3.
Which of the following would have the highest
Van’t Hoff factor (assuming complete dissociation)?
a) NaCl
b) CaCl₂
c) KCl
d) C₆H₁₂O₆
Answer: b) CaCl₂
4.
Which equation incorporates the Van’t Hoff factor
when calculating colligative properties?
a) ΔT = iK_f m
b) PV = nRT
c) E = mc²
d) Molarity = moles/volume
Answer: a) ΔT = iK_f m
5.
For a solution of Na₂SO₄, what is the theoretical
Van’t Hoff factor assuming full dissociation?
a) 1
b) 2
c) 3
d) 4
Answer: c) 3
24. What is the effect of increasing temperature on osmotic
pressure?
A) It increases
B) It decreases
C) It remains the same
D) It fluctuates
Answer: A) It increases
25. Which has the lowest freezing point?
A) 1.0 m NaCl
B) 1.0 m C₆H₁₂O₆
C) 1.0 m MgCl₂
D) 1.0 m CH₄
Answer: C) 1.0 m MgCl₂
26. The addition of a solute to a solvent will generally:
A) Increase freezing point
B) Lower osmotic pressure
C) Increase boiling point
D) Increase vapor pressure
Answer: C) Increase boiling point
27. Osmotic pressure is measured in:
A) Molarity
B) Atmospheres
C) Joules
D) Celsius
Answer: B) Atmospheres
28. A solvent with a dissolved solute will always have a:
A) Higher freezing point
B) Higher boiling point
C) Lower osmotic pressure
D) Lower boiling point
Answer: B) Higher boiling point
Effect of Van’t Hoff Factor on Colligative Properties
6.
7.
8.
9.
Which colligative property decreases with an
increasing Van’t Hoff factor?
a) Boiling point
b) Freezing point
c) Osmotic pressure
d) Vapor pressure lowering
Answer: b) Freezing point
Which of the following colligative properties is
directly proportional to the Van’t Hoff factor?
a) Boiling point elevation
b) Freezing point depression
c) Osmotic pressure
d) All of the above
Answer: d) All of the above
A 0.1 m solution of NaCl will have a greater boiling
point elevation than a 0.1 m solution of glucose
because:
a) NaCl dissociates into ions
b) Glucose is an electrolyte
c) NaCl has a higher molar mass
d) Glucose increases vapor pressure
Answer: a) NaCl dissociates into ions
Which of the following statements about the Van’t
Hoff factor is incorrect?
a) It accounts for ion pairing in real solutions
b) It is always equal to the number of ions in a
compound
c) It can be lower than expected due to incomplete
dissociation
d) It affects the magnitude of colligative properties
Answer: b) It is always equal to the number of ions
in a compound
10. Which of the following solutions will have the
highest freezing point depression?
a) 0.1 m NaCl
b) 0.1 m BaCl₂
c) 0.1 m C₆H₁₂O₆
d) 0.1 m K₃PO₄
Answer: d) 0.1 m K₃PO₄
Van’t Hoff Factor in Electrolytes and Nonelectrolytes
11. What is the Van’t Hoff factor for KCl in an ideal
solution?
a) 1
b) 2
c) 3
d) 4
Answer: b) 2
12. Which of the following compounds will NOT change
the Van’t Hoff factor when dissolved in water?
a) Na₂SO₄
b) C₆H₁₂O₆
c) MgCl₂
d) FeCl₃
Answer: b) C₆H₁₂O₆
13. For a solution of FeCl₃, what is the theoretical Van’t
Hoff factor?
a) 2
b) 3
c) 4
d) 5
Answer: c) 4
14. If the experimental Van’t Hoff factor for a strong
electrolyte is lower than expected, what might be
the reason?
a) The solute did not dissolve
b) Ion pairing occurred
c) The solution was too concentrated
d) The solvent evaporated
Answer: b) Ion pairing occurred
15. Which of the following compounds is expected to
have i ≈ 1 in an aqueous solution?
a) HCl
b) C₆H₁₂O₆
c) NaOH
d) Ca(NO₃)₂
Answer: b) C₆H₁₂O₆
Advanced Applications of Van’t Hoff Factor
16. What is the primary assumption in Van’t Hoff’s
factor calculations?
a) Complete dissociation of strong electrolytes
b) Ion pairing occurs frequently
c) Weak acids ionize fully
d) All solutions have the same freezing point
depression
Answer: a) Complete dissociation of strong
electrolytes
17. Which equation relates the Van’t Hoff factor to
osmotic pressure?
a) Π = iMRT
b) PV = nRT
c) ΔT = K_f m
d) ΔP = iK_b m
Answer: a) Π = iMRT
18. Which factor does NOT directly influence the
observed Van’t Hoff factor in real solutions?
a) Concentration of the solution
b) Temperature
c) Nature of the solute
d) Atmospheric pressure
Answer: d) Atmospheric pressure
19. Which solution will have the highest osmotic
pressure?
a) 0.1 m NaCl
b) 0.1 m C₆H₁₂O₆
c) 0.1 m MgCl₂
d) 0.1 m Al₂(SO₄)₃
Answer: d) 0.1 m Al₂(SO₄)₃
20. Why does Al₂(SO₄)₃ have a high Van’t Hoff factor?
a) It has strong intermolecular forces
b) It dissociates into five ions
c) It is a nonelectrolyte
d) It has low solubility
Answer: b) It dissociates into five ions
24. A 0.2 M solution of Al(NO₃)₃ has an osmotic
pressure of 12.3 atm at 25°C. What is the
experimental Van’t Hoff factor?
a) 3
b) 4
c) 2.5
d) 3.5
Answer: d) 3.5
Solution:
Freezing Point Depression & Boiling Point Elevation
21. A 0.2 m aqueous solution of NaCl has a freezing
point depression constant (Kf) of 1.86 °C·kg/mol.
Assuming complete dissociation, what is the
freezing point depression?
a) 0.372 °C
b) 0.744 °C
c) 1.86 °C
d) 3.72 °C
Answer: b) 0.744 °C
Solution:
22. What is the boiling point elevation for a 1.5 m
solution of CaCl₂ in water? (Kb for water = 0.512
°C·kg/mol, assume complete dissociation).
a) 0.512 °C
b) 1.024 °C
c) 2.304 °C
d) 1.536 °C
Answer: d) 1.536 °C
Colligative Property Comparisons
25. Which of the following solutions will have the
lowest freezing point?
a) 0.1 m NaCl
b) 0.1 m BaCl₂
c) 0.1 m AlCl₃
d) 0.1 m C₆H₁₂O₆
Answer: c) 0.1 m AlCl₃.
26. Which of the following 0.2 m solutions will have the
highest boiling point?
a) NaCl
b) CaCl₂
c) FeCl₃
d) Glucose
Answer: c) FeCl₃
Solution:
Molality and Van’t Hoff Factor Applications
Osmotic Pressure Calculations
23. Calculate the osmotic pressure of a 0.3 M K₂SO₄
solution at 27°C. (R = 0.0821 L·atm/mol·K, assume
complete dissociation).
a) 3.69 atm
b) 4.92 atm
c) 6.15 atm
d) 7.38 atm
Answer: c) 6.15 atm
Solution:
27. A solution contains 0.1 mol of NaCl dissolved in 500
g of water. What is the molality of the solution?
a) 0.1 m
b) 0.2 m
c) 0.4 m
d) 0.5 m
Answer: b) 0.2 m
28. For a 1.0 m solution of KCl, the observed freezing
point depression is 3.2°C instead of the expected
3.72°C. What is the experimental Van’t Hoff factor?
a) 1.5
b) 1.7
c) 1.9
d) 2.0
Answer: b) 1.7
Solution:
3. What is the activity coefficient (γ) in a solution?
A. A correction factor for non-ideal behavior
B. A measure of solute concentration
C. The ratio of solute to solvent
D. A constant value for all solutions
Answer: A. A correction factor for non-ideal behavior
Real vs. Theoretical Van’t Hoff Factor
29. Which of the following best explains why the
experimental Van’t Hoff factor is lower than the
theoretical value?
a) The solution is too dilute
b) Some ions recombine due to interionic attraction
c) The solvent does not dissolve the solute
completely
d) The solute does not dissociate at all
Answer: b) Some ions recombine due to interionic
attraction
30. A solution of 0.5 m MgCl₂ in water has an observed
boiling point elevation of 0.64°C. (Kb for water =
0.512 °C·kg/mol). What is the experimental Van’t
Hoff factor?
a) 1.5
b) 2.5
c) 2.8
d) 3.0
Answer: c) 2.8
Solution:
4. In an ideal solution, what is the value of the activity
coefficient (γ)?
A. 0
B. 1
C. Greater than 1
D. Less than 1
Answer: B. 1
5. What happens to the activity coefficient as ionic strength
increases?
A. It increases
B. It decreases
C. It remains constant
D. It fluctuates randomly
Answer: B. It decreases
6. Which equation relates activity to molality for an
electrolyte solution?
A. a = γ × m
B. a = m / γ
C. a = γ × P
D. a = m × P
Answer: A. a = γ × m
7. Which colligative property is most directly related to
solute activity?
1. What does the activity of a solute in a solution represent?
A. The actual concentration of the solute
B. The effective concentration accounting for interactions
C. The number of moles of solute per liter
D. The weight of solute in grams per liter
Answer: B. The effective concentration accounting for
interactions
2. How is activity (a) of a solute related to its concentration
(C) in an ideal solution?
A. a = C × P
B. a = γ × C
C. a = C / γ
D. a = P / C
Answer: B. a = γ × C
A. Osmotic pressure
B. Vapor pressure lowering
C. Freezing point depression
D. All of the above
Answer: D. All of the above
8. Why does the presence of solutes lower the freezing point
of a solution?
A. Solute molecules interfere with solvent crystallization
B. Solute increases the solution temperature
C. Solutes increase vapor pressure
D. Solutes make the solution more viscous
Answer: A. Solute molecules interfere with solvent
crystallization
9. How does increasing solute activity affect osmotic
pressure?
A. Increases it
B. Decreases it
C. Has no effect
D. Causes random fluctuations
Answer: A. Increases it
10. What is the main factor affecting solute activity in a
solution?
17. What is the activity of a solute in a highly dilute
solution?
A. Temperature
B. Pressure
C. Ionic interactions
D. Color of the solution
Answer: C. Ionic interactions
A. Nearly equal to its concentration
B. Much greater than its concentration
C. Close to zero
D. Unrelated to concentration
Answer: A. Nearly equal to its concentration
11. The Debye-Hückel equation is used to calculate:
18. The van’t Hoff factor (i) influences which colligative
property?
A. Activity coefficients of electrolytes
B. Freezing point depression
C. Osmotic pressure
D. Boiling point elevation
Answer: A. Activity coefficients of electrolytes
12. In non-ideal solutions, why does activity differ from
concentration?
A. Due to intermolecular forces
B. Due to temperature fluctuations
C. Because of solvent evaporation
D. Because concentration remains constant
Answer: A. Due to intermolecular forces
13. What is the typical range for the activity coefficient in
real solutions?
A. 0 < γ ≤ 1
B. 1 < γ < 10
C. γ = 0
D. γ = ∞
Answer: A. 0 < γ ≤ 1
14. What effect does increasing ionic strength have on
solute activity?
A. Freezing point depression
B. Osmotic pressure
C. Boiling point elevation
D. All of the above
Answer: D. All of the above
19. The concept of solute activity is most relevant in which
type of solution?
A. Dilute solutions
B. Concentrated solutions
C. Gaseous solutions
D. Solid solutions
Answer: B. Concentrated solutions
20. In electrolyte solutions, why is activity used instead of
concentration?
A. Ion interactions cause non-ideal behavior
B. Concentration changes over time
C. The solvent absorbs solute molecules
D. The solute dissolves completely
Answer: A. Ion interactions cause non-ideal behavior
21. What is fugacity in relation to solute activity?
A. Decreases it
B. Increases it
C. No effect
D. Makes it unpredictable
Answer: A. Decreases it
A. The effective pressure in gaseous systems
B. The weight of solute per volume
C. The ability of a solute to dissolve
D. The freezing point of a solution
Answer: A. The effective pressure in gaseous systems
15. Which factor most influences the deviation of activity
from concentration in an electrolyte solution?
22. Which factor does NOT affect solute activity?
A. The charge of the ions
B. The solvent color
C. The gas dissolved in the solution
D. The stirring speed
Answer: A. The charge of the ions
16. How does adding an inert salt affect the activity of an
ionic solute?
A. Lowers activity by increasing ionic strength
B. Increases activity by adding more ions
C. Has no effect on activity
D. Destroys solute molecules
Answer: A. Lowers activity by increasing ionic strength
A. Temperature
B. Molecular weight
C. Ionic strength
D. Dielectric constant of solvent
Answer: B. Molecular weight
23. Which law is modified to incorporate activity coefficients
in equilibrium calculations?
A. Raoult’s Law
B. Henry’s Law
C. Le Chatelier’s Principle
D. Mass Action Law
Answer: D. Mass Action Law
24. Which type of solute has the most deviation from ideal
behavior?
1.
What does the Debye-Hückel theory primarily
describe?
a) The behavior of ideal gases
b) The interactions between ions in electrolyte
solutions
c) The kinetics of chemical reactions
d) The structure of covalent compounds
Answer: b) The interactions between ions in
electrolyte solutions
2.
What fundamental concept does the Debye-Hückel
theory introduce?
a) Ionic strength of a solution
b) Van der Waals forces
c) Bohr’s atomic model
d) None of the above
Answer: a) Ionic strength of a solution
3.
According to Debye-Hückel theory, what is
responsible for deviations from ideal behavior in
electrolyte solutions?
a) Molecular size of the solvent
b) Ion-solvent interactions
c) Electrostatic interactions between ions
d) Temperature fluctuations
Answer: c) Electrostatic interactions between ions
4.
The Debye-Hückel limiting law applies best to
which type of solution?
a) Highly concentrated solutions
b) Dilute electrolyte solutions
c) Pure solvents
d) Solutions containing only non-electrolytes
Answer: b) Dilute electrolyte solutions
5.
Which of the following is a key assumption of the
Debye-Hückel theory?
a) Ions behave as point charges
b) Ions have fixed positions in solution
c) The solvent is an ideal gas
d) Electrostatic forces are negligible
Answer: a) Ions behave as point charges
6.
In the Debye-Hückel equation, what does the term
"ionic strength" (I) represent?
a) The sum of molar concentrations of all species
b) A measure of the average electrostatic effect of
ions in solution
c) The pH of the solution
d) The total pressure exerted by ions
Answer: b) A measure of the average electrostatic
effect of ions in solution
A. Non-electrolyte
B. Strong electrolyte
C. Weak electrolyte
D. Gaseous solute
Answer: B. Strong electrolyte
25. What is the activity of a pure solvent?
A. 0
B. 1
C. ∞
D. Equal to its concentration
Answer: B. 1
26. What is the effect of increasing temperature on the
activity coefficient of most solutes?
A. Increases
B. Decreases
C. Stays the same
D. Randomly fluctuates
Answer: B. Decreases
27. When an electrolyte dissolves, why does its activity
coefficient decrease?
A. Ion-ion interactions reduce effective concentration
B. The solute forms a new phase
C. The solute evaporates
D. The solvent absorbs the solute
Answer: A. Ion-ion interactions reduce effective
concentration
28. Which property is NOT influenced by solute activity?
A. Vapor pressure
B. Surface tension
C. Boiling point
D. Freezing point
Answer: B. Surface tension
29. What happens to solute activity when a strong acid is
added to water?
A. Increases
B. Decreases
C. Stays the same
D. Depends on the acid concentration
Answer: D. Depends on the acid concentration
30. The concept of activity is most useful in which field?
A. Thermodynamics
B. Quantum mechanics
C. Electromagnetism
D. Optics
Answer: A. Thermodynamics
7.
What is the mathematical expression for ionic
strength (I)?
Answer: b)
8.
The Debye-Hückel equation modifies which of the
following properties of an electrolyte solution?
a) Vapor pressure
b) Activity coefficient
c) Melting point
d) Boiling point
Answer: b) Activity coefficient
9.
What happens to the activity coefficient of an ion
as the ionic strength increases?
a) It increases
b) It decreases
c) It remains constant
d) It becomes zero
Answer: b) It decreases
10. What is the effect of higher ionic strength on
electrostatic interactions between ions?
a) Increases interactions
b) Decreases interactions
c) No effect
d) Causes precipitation
Answer: b) Decreases interactions
11. The Debye-Hückel theory is most accurate for
which type of electrolytes?
a) Strong electrolytes in highly concentrated
solutions
b) Weak electrolytes in concentrated solutions
c) Strong electrolytes in dilute solutions
d) Non-electrolytes
Answer: c) Strong electrolytes in dilute solutions
12. What is the unit of ionic strength (I)?
a) Molarity (M)
b) Molarity squared (M²)
c) Molality (m)
d) No units
Answer: a) Molarity (M)
13. Which parameter in the Debye-Hückel equation
depends on temperature and dielectric constant?
a) The Debye length
b) The ionic radius
c) The charge of ions
d) The activity coefficient
Answer: a) The Debye length
14. What is the physical significance of the Debye
length?
a) It represents the distance over which electrostatic
interactions persist
b) It measures the molar volume of electrolytes
c) It determines the speed of ionic diffusion
d) It quantifies solubility
Answer: a) It represents the distance over which
electrostatic interactions persist
15. According to Debye-Hückel theory, the potential
around an ion is modified by:
a) Other ions in the solution
b) Only water molecules
c) Van der Waals forces
d) Hydrogen bonding
Answer: a) Other ions in the solution
16. The Debye-Hückel theory assumes that the solvent
acts as a:
a) Continuous medium
b) Collection of rigid spheres
c) Charged lattice
d) Neutral buffer
Answer: a) Continuous medium
17. What happens to the Debye length as ionic strength
increases?
a) It increases
b) It decreases
c) It remains constant
d) It fluctuates randomly
Answer: b) It decreases
18. What does the activity coefficient approach in an
ideal solution?
a) 0
b) 1
c) -1
d) Infinity
Answer: b) 1
19. Which of the following affects the ionic strength of
a solution?
a) Concentration of ions
b) Charge of ions
c) Both a and b
d) Neither a nor b
Answer: c) Both a and b
20. Which factor does NOT influence the validity of
Debye-Hückel theory?
a) Solvent dielectric constant
b) Concentration of electrolytes
c) Temperature
d) The color of the solution
Answer: d) The color of the solution
21. What is the main limitation of the Debye-Hückel
theory?
a) It only applies to gases
b) It is inaccurate for concentrated solutions
c) It ignores charge effects
d) It applies only to non-electrolytes
Answer: b) It is inaccurate for concentrated solutions
22. Which scientist(s) developed the Debye-Hückel
theory?
a) Niels Bohr and Albert Einstein
b) Peter Debye and Erich Hückel
c) Arrhenius and Van't Hoff
d) Gibbs and Helmholtz
Answer: b) Peter Debye and Erich Hückel
23. Which equation describes the activity coefficient in
Debye-Hückel theory?
Answer: a)
24. What happens to the activity coefficient when ion
charge increases?
a) It decreases
b) It increases
c) It remains the same
d) It becomes infinite
Answer: a) It decreases
Multiple Choice Questions (MCQs) on
Colligative Properties, Van’t Hoff Factor,
Activity, and Debye-Hückel Theory
Colligative Properties
1. Which of the following is not a colligative
property?
a) Vapor pressure lowering
b) Boiling point elevation
c) Freezing point depression
d) Enthalpy change of solution
Answer: d) Enthalpy change of solution
2. The boiling point elevation is directly
proportional to:
a) The molality of the solute
b) The molarity of the solute
c) The density of the solvent
d) The volume of the solution
Answer: a) The molality of the solute
3. When a non-volatile solute is added to a
solvent, the vapor pressure of the solution:
a) Increases
b) Decreases
c) Remains the same
d) Increases only at high temperatures
Answer: b) Decreases
4. Freezing point depression occurs because:
a) Solute particles increase the kinetic
energy of solvent molecules
b) The presence of solute disrupts the
formation of a solid lattice
c) Solute increases the vapor pressure of the
solution
d) Solute molecules prevent evaporation
Answer: b) The presence of solute disrupts
the formation of a solid lattice
5. Which colligative property is the basis for
determining the molar mass of an unknown
solute?
a) Boiling point elevation
b) Freezing point depression
c) Osmotic pressure
d) All of the above
Answer: d) All of the above
6. Raoult’s Law states that the vapor pressure
of a solution is:
a) Equal to the vapor pressure of the pure
solvent
b) Higher than that of the pure solvent
c) Lower than that of the pure solvent
d) Unaffected by the solute concentration
Answer: c) Lower than that of the pure
solvent
7. Which of the following expressions
correctly represents osmotic pressure
(π\pi)?
a) π=iMRT\pi = iMRT
b) π=iRT/m\pi = iRT/m
c) π=MRT\pi = MRT
d) π=PRT/i\pi = PRT/i
Answer: a) π=iMRT\pi = iMRT
8. If two solutions have the same osmotic
pressure, they are said to be:
a) Hypotonic
b) Isotonic
c) Hypertonic
d) Colloidal
Answer: b) Isotonic
9. The colligative properties depend on:
a) The nature of the solute
b) The type of solvent
c) The number of solute particles
d) The polarity of the solvent
Answer: c) The number of solute particles
10. Electrolytes show abnormal colligative
properties due to:
a) Their ability to dissolve
b) Ionization in solution
c) High boiling points
d) Large molecular sizes
Answer: b) Ionization in solution
Van’t Hoff Factor
11. Van’t Hoff factor (ii) represents:
a) The number of moles of solute in solution
b) The ratio of actual particles to expected
particles
c) The concentration of solvent molecules
d) The change in vapor pressure
Answer: b) The ratio of actual particles to
expected particles
12. The Van’t Hoff factor for a non-electrolyte
in solution is:
a) 0
b) 1
c) Greater than 1
d) Less than 1
Answer: b) 1
13. What is the Van’t Hoff factor (ii) for NaCl
in aqueous solution assuming complete
dissociation?
a) 1
b) 2
c) 3
d) 4
Answer: b) 2
14. The Van’t Hoff factor for
AlCl3\text{AlCl}_3 is:
a) 2
b) 3
c) 4
d) 5
Answer: c) 4
15. If a solute undergoes association in solution,
the Van’t Hoff factor will be:
a) Greater than 1
b) Equal to 1
c) Less than 1
d) Zero
Answer: c) Less than 1
Activity and Activity Coefficients
16. Activity is defined as the:
a) Effective concentration of a species in
solution
b) Ratio of solute to solvent
c) Molarity of a solution
d) Weight of solute in grams
Answer: a) Effective concentration of a
species in solution
17. The activity coefficient (γ\gamma)
approaches 1 when:
a) The solution is highly concentrated
b) The solution is ideal or very dilute
c) The solution has strong intermolecular
forces
d) The Van’t Hoff factor is large
Answer: b) The solution is ideal or very
dilute
18. The Debye-Hückel limiting law is used to
determine:
a) The activity coefficient of ions
b) The boiling point of a solution
c) The enthalpy of reaction
d) The solubility of non-electrolytes
Answer: a) The activity coefficient of ions
19. As ionic strength increases, the activity
coefficient:
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
Answer: b) Decreases
20. The relationship between activity (aa) and
concentration (cc) is given by:
a) a=γca = \gamma c
b) a=c/γa = c/\gamma
c) a=cγ2a = c \gamma^2
d) a=γ2/ca = \gamma^2/c
Answer: a) a=γca = \gamma c
Debye-Hückel Theory
21. The Debye-Hückel Theory explains:
a) The colligative properties of strong
electrolytes
b) The behavior of dilute solutions of strong
electrolytes
c) The dissociation of weak acids
d) The formation of non-ionic solutions
Answer: b) The behavior of dilute solutions
of strong electrolytes
22. Ionic strength is given by:
a) I=0.5∑cizi2I = 0.5 \sum c_i z_i^2
b) I=0.5∑ciziI = 0.5 \sum c_i z_i
c) I=∑ciziI = \sum c_i z_i
d) I=∑ci2zi2I = \sum c_i^2 z_i^2
Answer: a) I=0.5∑cizi2I = 0.5 \sum c_i
z_i^2
23. In Debye-Hückel theory, the charge
atmosphere around an ion is:
a) Uniform
b) Oppositely charged
c) Positively charged
d) Negatively charged
Answer: b) Oppositely charged
24. The Debye length (κ−1\kappa^{-1})
represents:
a) The effective distance of electrostatic
interactions
b) The size of the solute molecule
c) The rate of dissolution
d) The conductivity of the solution
Answer: a) The effective distance of
electrostatic interactions
25. The Debye-Hückel equation is most accurate
for:
a) Concentrated solutions
b) Dilute solutions
c) All solutions
d) None of the above
Answer: b) Dilute solutions
This covers fundamental concepts from colligative
properties to Debye-Hückel theory! Let me know if
you need adjustments.