Vapour pressure of solutions, Raoult's law, ideal and non-ideal solutions, colligative properties and determination of molecular mass, van't Hoff factor - One Line Questions

1. For NaCl, which dissociates into Na⁺ and Cl⁻ ions, the theoretical van't Hoff factor is: — 2
2. If a solute associates to form 'n' particles in solution, and the degree of association is α, the van't Hoff factor 'i' is given by: — 1 + α(1/n - 1)
3. If a solute dissociates into 'n' ions in solution, and the degree of dissociation is α, the van't Hoff factor 'i' is given by: — 1 + α(n-1)
4. Which of the following pairs forms a non-ideal solution with negative deviation? — Acetone and Carbon disulphide
5. Which of the following pairs forms a non-ideal solution with positive deviation? — Acetone and Ethanol
6. Azeotropes are solutions that: — Boil at a constant temperature and have the same composition in the liquid and vapour phases.
7. A solution of glucose in water and a solution of sucrose in water, both having the same molar concentration, will have the same: — Osmotic pressure
8. How does the vapour pressure of a pure solvent change with increasing temperature? — Increases
9. The determination of molecular mass of a solute using colligative properties relies on the fact that colligative properties are: — Dependent on the number of solute particles.
10. The van't Hoff factor (i) is used to account for the: — Association or dissociation of solute particles in solution.
11. Elevation of boiling point (ΔT_b) is directly proportional to the molality (m) of the solution. The proportionality constant is known as: — Ebullioscopic constant (K_b)
12. Depression of freezing point (ΔT_f) is directly proportional to the molality (m) of the solution. The proportionality constant is known as: — Cryoscopic constant (K_f)
13. For a solution of acetic acid in water, which undergoes partial dissociation, the van't Hoff factor (i) is typically: — Greater than 1 but less than 2
14. A solution that boils at a temperature higher than the boiling point of the pure solvent is said to exhibit: — Boiling point elevation
15. For a non-electrolyte solute that does not dissociate or associate in solution, the van't Hoff factor (i) is: — Equal to 1
16. The vapour pressure of a solution is always lower than that of the pure solvent at the same temperature due to: — Presence of non-volatile solute particles on the surface.
17. When a non-volatile solute is dissolved in a solvent, the vapour pressure of the solvent: — Decreases
18. Osmotic pressure is particularly useful for determining the molecular mass of: — Polymers and macromolecules
19. Which of the following statements about Raoult's law is INCORRECT? — It describes the behaviour of real solutions under all conditions.
20. The unit of ebullioscopic constant (K_b) is: — K mol kg⁻¹
21. The unit of cryoscopic constant (K_f) is: — K mol kg⁻¹
22. To determine the molecular mass of a non-volatile solute using the elevation of boiling point method, the formula is: — M = (K_b * w) / (ΔT_b * W)
23. In the formula for determining molecular mass from freezing point depression (M = (K_f * w) / (ΔT_f * W)), 'w' represents: — Mass of the solute in grams
24. According to Raoult's law, the partial vapour pressure of a volatile component in a solution is directly proportional to its: — Mole fraction in the liquid phase
25. Minimum boiling azeotropes are formed by solutions showing: — Positive deviation from Raoult's law
26. An ideal solution is one that: — Obeys Raoult's law under all conditions of temperature and concentration.
27. A non-ideal solution is one that: — Does not obey Raoult's law.
28. Non-ideal solutions that show positive deviation from Raoult's law exhibit: — P_total > P_A° * x_A + P_B° * x_B
29. For a binary solution of two volatile components A and B, Raoult's law can be expressed as: — P_total = P_A° * x_A + P_B° * x_B
30. Non-ideal solutions that show negative deviation from Raoult's law exhibit: — P_total < P_A° * x_A + P_B° * x_B
31. For a dilute solution, the relative lowering of vapour pressure is given by: — P° - P_s / P° = n / (n+N)
32. For a non-ideal solution showing negative deviation, the enthalpy of mixing (ΔH_mix) is typically: — Negative
33. Maximum boiling azeotropes are formed by solutions showing: — Negative deviation from Raoult's law
34. Which of the following is NOT a colligative property? — Osmotic pressure
35. Which colligative property is generally preferred for determining the molecular mass of macromolecules? — Osmotic pressure
36. The relative lowering of vapour pressure of a solvent is equal to the mole fraction of the: — Solute
37. Reverse osmosis is a process where: — Solvent moves from a region of lower solute concentration to a region of higher solute concentration.
38. What is the total vapour pressure of an ideal solution according to Raoult's law? — Sum of partial pressures of individual components
39. The depression in freezing point of a solvent upon addition of a solute is a colligative property because it depends on: — The concentration of the solute particles.
40. Colligative properties depend on: — The total number of solute particles, irrespective of their nature.
41. If the degree of dissociation of an electrolyte is 1 (complete dissociation), the van't Hoff factor 'i' is equal to: — The number of ions produced per molecule
42. What is the definition of vapour pressure of a liquid? — The pressure exerted by the liquid molecules in the gaseous state in equilibrium with the liquid at a given temperature.
43. Isotonic solutions are solutions that have: — The same osmotic pressure.
44. For a non-ideal solution showing positive deviation, the intermolecular forces between solvent-solvent and solute-solute are generally: than solvent-solute interactions. — Stronger
45. Which of the following is a characteristic of an ideal solution? — ΔH_mix = 0, ΔV_mix = 0
46. The van't Hoff factor can be used to modify the colligative property expressions. For example, elevation of boiling point becomes: — ΔT_b = i * K_b * m
47. What is the relationship between osmotic pressure (Π), molar concentration (C), gas constant (R), and absolute temperature (T)? — Π = CRT
48. Osmotic pressure (Π) of a solution is given by the formula: — Π = nRT / V
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