The boiling point of a solution is always higher than the pure solvent. The boiling point increases as we add non-volatile solutes in a pure solvent. The elevation of boiling point is dependent on the number of solute particles and not on their nature. For dilute solutions, the elevation in boiling point is proportional to the molal concentration of the solute. The boiling point elevation of a solution is a colligative property, as it depends on the number of solute molecules rather than their nature.
1. With evaporation, the boiling point of a solution
(a) Decreases
(b) Increases
(c) Becomes half
(d) Remains the same
2. Which of the following is not a colligative property?
(a) Surface tension
(b) Osmotic pressure
(c) Vapour pressure depression
(d) Boiling point elevation
3. The boiling point elevation constant of water is ______ K kg mol-1.
(a) 51.2
(b) 0.512
(c) 5.12
(d) 0.0512
4. Find the boiling point of 0.1 molal aqueous NaCl solution, if the molal elevation constant of water is 0.51.
(a) 100.1 ℃
(b) 100.2 ℃
(c) 100.5 ℃
(d) 100.05 ℃
5. Which of the following colligative properties is the best method for the determination of molecular weight of proteins and polymers?
(a) Lowering in vapour pressure
(b) Osmotic pressure
(c) Elevation in boiling point
(d) Lowering in freezing point
6. Which one of the following statements is true, if the boiling point of 0.2 mol kg-1 solution of Y in water is less than the equimolal solution of X in water?
(a) Y undergoes dissociation in water, while X remains the same.
(b) Molecular mass of Y is less than the molecular mass of X.
(c) X undergoes dissociation in water.
(d) Molecular mass of Y is greater than the molecular mass of X.
7. An ideal solution is formed when its components have
(a) no enthalpy change on mixing
(b) no volume change on mixing
(c) high solubility
(d) Both (a) and (b)
8. A solution of urea (mol. mass 56 g mol-1) boils at 100.18°C at atmospheric pressure. If Kf and Kb for water are 1.86 and 0.512 K kg mol-1, respectively, the above solution will freeze at
(a) -0.654°C
(b) 0.654°C
(c) -6.54°C
(d) 6.54°C
9. In which of the solvent the boiling point elevation will be maximum for a solution of 1 molal concentration of a solute?
(a) Acetone
(b) Ethyl alcohol
(c) Chloroform
(d) Benzene
10. When 0.15 g of a solute is dissolved in 15 g of solvent, the boiling point of the solution becomes 0.216°C higher than that of the pure solvent. Find the molecular weight of the substance, if molal elevation constant for the solvent is 2.16°C.
(a) 1000
(b) 100
(c) 1.01
(d) 10.1
Answer
|
1. (b) |
2. (a) |
3. (b) |
4. (d) |
5. (b) |
|
6. (c) |
7. (d) |
8. (a) |
9. (c) |
10. (b) |
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