Solutions (Class 12) — 30 Question Quiz

Solutions (Class 12 NCERT) — 30 Question Quiz

Revision: concentration terms, Raoult’s/Henry’s laws, colligative properties, van't Hoff factor & practical concepts.

1. A homogeneous mixture of two or more non-reacting substances is called a:

Compound Solution Colloid Suspension

2. The major component of a solution is called the:

Solute Solvent Impurity Carrier

3. Molality (m) is defined as:

Moles solute per liter of solution Moles solute per kg of solvent Mass percent Moles of solvent per mole solute

4. Which concentration term is temperature independent?

Molarity Molality Volume percent Parts per million

5. Mole fraction (χ) of components in a solution sums to:

0 1 100 Depends on temperature

6. Henry’s law relates the partial pressure of a gas above solution to:

Mole fraction of gas in solution Molality of solute Molar mass of solvent Density

7. Increasing pressure on a gas-liquid system (at constant T) generally:

Decreases gas solubility Increases gas solubility Has no effect Destroys solvent

8. Raoult’s law for a volatile component A is:

PA = PA° × χA PA = PA° / χA PA = χB × PB° PA = constant

9. Relative lowering of vapor pressure (ΔP/P°) equals:

Mole fraction of solvent Mole fraction of solute Mass percent Molality

10. An ideal solution has which mixing enthalpy (ΔHmix)?

Positive Negative Zero Depends on pressure

11. Colligative properties depend on:

Nature of solute particles Number of solute particles only Type of solvent only Temperature only

12. Elevation of boiling point ΔTb is proportional to:

Molarity Molality Mole fraction of solvent Pressure only

13. Osmotic pressure (π) is given by van’t Hoff equation as:

π = nRT/V π = CRT π = Kb m π = ΔTf × Kf

14. Which colligative property is preferred to determine molar mass of polymers?

Lowering of vapor pressure Boiling point elevation Osmotic pressure Freezing point depression

15. A solution isotonic with blood (approx) is:

0.5% NaCl (w/v) 0.9% NaCl (w/v) 5% NaCl 10% NaCl

16. Reverse osmosis (RO) is primarily used for:

Concentrating blood Desalination of seawater Boiling solvent Increasing vapor pressure

17. Abnormal molar masses in colligative measurements are often due to:

Association or dissociation of solute Constant temperature Use of volatile solute Ideal behaviour

18. The van’t Hoff factor (i) for a non-electrolyte is:

0 1 2 Depends on temperature

19. For NaCl (ideal dissociation) expected i value is:

1 2 3 0.5

20. If χsolvent = 0.8, then χsolute equals:

0.2 0.8 1.0 Depends on molarity

21. Azeotropes are mixtures that:

Distil with changing composition Boil at constant T and distil without change in composition Never boil Only occur in solid mixtures

22. Positive deviation from Raoult’s law occurs when:

A–B attractions > A–A and B–B A–B attractions < A–A and B–B Solution is ideal Only at low T

23. A mixture showing negative deviation typically forms which azeotrope?

Minimum boiling azeotrope Maximum boiling azeotrope No azeotrope Only solid azeotrope

24. Which property is often used graphically to find boiling point elevation?

Vapour pressure vs temperature plot Conductivity vs temperature Viscosity vs pressure pH vs concentration

25. Osmosis occurs through a:

Filter paper Semipermeable membrane Porous rock Glass wool

26. If a solute associates (dimerizes) in solution, the van’t Hoff factor i will be:

>1 <1 =1 Zero

27. For K₂SO₄ ideal dissociation gives i =:

2 3 4 1

28. Which effect does adding a non-volatile solute have on solvent vapor pressure?

Increases vapor pressure Lowers vapor pressure No change Makes it equal to atmospheric pressure

29. Which solvent property determines Kb and Kf values?

Nature of solvent Atmospheric pressure only Concentration of solute only Color of solvent

30. Why does CaCl₂ lower freezing point more effectively than NaCl on equal molal basis?

Because CaCl₂ dissociates into more ions (i ≈ 3) Because CaCl₂ is volatile Because CaCl₂ is non-electrolyte Because NaCl vaporizes