Q1. Which of the following statements about solutions is true? (2023)
Solution:
Both statements are true; solutes affect the colligative properties of solvents.
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Q2. What is the van 't Hoff factor (i) for a non-electrolyte solute? (2023)
Solution:
The van 't Hoff factor (i) for a non-electrolyte solute is 1, as it does not dissociate into ions.
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Q3. What is the van 't Hoff factor (i) for a strong electrolyte like Na2SO4 in solution? (2023)
Solution:
Na2SO4 dissociates into 3 ions (2 Na⁺ and 1 SO4²⁻), so i = 3.
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Q4. What is the van 't Hoff factor (i) for a solution of glucose (C6H12O6)? (2023)
Solution:
Glucose does not dissociate in solution, so the van 't Hoff factor (i) = 1.
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Q5. Which of the following solutions has the highest boiling point elevation? (2020)
Solution:
Boiling point elevation is proportional to the number of particles in solution. CaCl2 dissociates into 3 ions (1 Ca²⁺ and 2 Cl⁻), giving the highest elevation.
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Q6. If the freezing point of pure water is 0 °C, what will be the freezing point of a solution containing 1 mole of NaCl in 1 kg of water? (2023)
Solution:
Freezing point depression = i * Kf * m = 2 * 1.86 °C kg/mol * 1 mol/kg = 3.72 °C. Thus, freezing point = 0 - 3.72 = -3.72 °C.
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Q7. What is the osmotic pressure of a solution containing 0.5 moles of solute in 1 liter of solution at 25 °C? (R = 0.0821 L·atm/(K·mol)) (2021)
Q8. If 1 mole of a non-volatile solute is dissolved in 1 kg of water, what is the expected freezing point depression? (2019)
Solution:
Freezing point depression (ΔTf) = i * Kf * m = 1 * 1.86 °C kg/mol * 1 mol/kg = 1.86 °C.
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Q9. If the freezing point of a solution is -5°C, what is the molality of the solution if the freezing point depression constant (Kf) is 1.86°C kg/mol? (2022)
Solution:
ΔTf = Kf * m; -5 = -1.86 * m; m = 5 / 1.86 = 2.68 m.
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Q10. What is the osmotic pressure of a 0.5 M NaCl solution at 25°C? (R = 0.0821 L·atm/(K·mol)) (2023)
