41. The osmotic pressure of a solution is related to the:
A. Volume of solvent
B. Concentration of solute particles
C. Nature of solute
D. Molecular weight of solute
Answer: B. Concentration of solute particles
Explanation:
Osmotic pressure is directly proportional to the concentration of solute particles in the solution. It is a colligative property, meaning it depends only on the number of solute particles.
42. Which of the following will have the lowest freezing point?
A. 0.1 M urea
B. 0.1 M glucose
C. 0.1 M NaCl
D. 0.1 M K₂SO₄
Answer: D. 0.1 M K₂SO₄
Explanation:
K₂SO₄ dissociates into three ions (2 K⁺ and 1 SO₄²⁻), creating the largest number of particles in the solution. Since freezing point depression is proportional to the number of particles, K₂SO₄ will cause the greatest freezing point depression.
43. When comparing solutions of the same concentration, which one will have the highest boiling point?
A. 1 M glucose
B. 1 M NaCl
C. 1 M CaCl₂
D. 1 M urea
Answer: C. 1 M CaCl₂
Explanation:
CaCl₂ dissociates into three ions (Ca²⁺ and 2 Cl⁻), producing the highest number of solute particles. This will result in the greatest elevation in boiling point, since boiling point elevation is proportional to the number of particles in solution.
44. In an ideal solution, the partial vapor pressure of a component is:
A. Higher than predicted by Raoult’s law
B. Lower than predicted by Raoult’s law
C. Equal to its mole fraction multiplied by the vapor pressure of the pure component
D. Independent of its mole fraction
Answer: C. Equal to its mole fraction multiplied by the vapor pressure of the pure component
Explanation:
According to Raoult’s law, in an ideal solution, the partial vapor pressure of a component is proportional to its mole fraction and the vapor pressure of the pure component.
45. The colligative property of vapor pressure lowering is used to:
A. Determine the boiling point of a solvent
B. Determine the molar mass of a solute
C. Determine the molecular structure of a solute
D. Determine the density of a solvent
Answer: B. Determine the molar mass of a solute
Explanation:
Vapor pressure lowering is a colligative property that can be used to determine the molar mass of a solute by measuring the change in vapor pressure when a solute is added to a solvent.
46. A solution that exhibits a negative deviation from Raoult’s law has:
A. Weaker solute-solvent interactions
B. Stronger solute-solvent interactions
C. No solute-solvent interactions
D. The same solute-solvent and solvent-solvent interactions
Answer: B. Stronger solute-solvent interactions
Explanation:
Negative deviation from Raoult’s law occurs when the solute-solvent interactions are stronger than the solute-solute and solvent-solvent interactions, leading to a lower vapor pressure than expected.
47. The molal depression constant (K_f) depends upon:
A. The nature of the solute
B. The nature of the solvent
C. The concentration of the solution
D. The temperature of the solution
Answer: B. The nature of the solvent
Explanation:
The molal depression constant (K_f) is a property of the solvent and depends only on the nature of the solvent. It represents the freezing point depression per molal concentration of a solute.
48. Colligative properties include all except:
A. Boiling point elevation
B. Freezing point depression
C. Surface tension
D. Osmotic pressure
Answer: C. Surface tension
Explanation:
Surface tension is not a colligative property. Colligative properties (boiling point elevation, freezing point depression, and osmotic pressure) depend on the number of solute particles in a solution.
49. Which of the following solutions will have the highest boiling point?
A. 0.1 M glucose
B. 0.1 M NaCl
C. 0.1 M MgCl₂
D. 0.1 M urea
Answer: C. 0.1 M MgCl₂
Explanation:
MgCl₂ dissociates into three ions (Mg²⁺ and 2 Cl⁻), resulting in the largest number of solute particles in solution. The more particles there are, the greater the boiling point elevation.
50. The van’t Hoff factor (i) for a substance that does not dissociate in solution is:
A. 0
B. 1
C. 2
D. 3
Answer: B. 1
Explanation:
For substances that do not dissociate in solution, the van’t Hoff factor (i) is 1, as the number of particles in the solution is the same as the number of molecules of the solute.
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