Class 12 Chemistry MCQ – Solutions

1. A solution which cannot dissolve any more solute at a given temperature is termed:

a) Unsaturated
b) Saturated
c) Supersaturated
d) Diluted

Answer:

b) Saturated

Explanation:

A saturated solution is one in which no more solute can be dissolved at a particular temperature.

2. The unit of molality (m) is:

a) mol/kg
b) mol/L
c) g/mol
d) L/mol

Answer:

a) mol/kg

Explanation:

Molality is defined as the number of moles of solute per kilogram of solvent.

3. Which of the following expresses the concentration of a solution in volume/volume percentage?

a) Mass/Volume percent
b) Volume/Volume percent
c) Mass/Mass percent
d) None of the above

Answer:

b) Volume/Volume percent

Explanation:

Volume/Volume percent expresses the concentration of a solution where both solute and solvent are in liquid form.

4. Raoult's Law is valid for:

a) Non-volatile solutes
b) Volatile solutes
c) Both volatile and non-volatile solutes
d) None of the above

Answer:

c) Both volatile and non-volatile solutes

Explanation:

Raoult's Law is applicable for both volatile and non-volatile solutes in a solution.

5. A decrease in vapor pressure of a solution compared to that of the pure solvent is related to:

a) Elevation in boiling point
b) Depression in freezing point
c) Osmotic pressure
d) Both a and b

Answer:

d) Both a and b

Explanation:

Both elevation in boiling point and depression in freezing point are colligative properties related to the decrease in vapor pressure of a solution.

6. Henry's Law relates:

a) Solubility and pressure
b) Temperature and solubility
c) Vapor pressure and solubility
d) Vapor pressure and mole fraction

Answer:

a) Solubility and pressure

Explanation:

Henry's Law establishes a relationship between the solubility of a gas in a liquid and the partial pressure of that gas above the liquid.

7. The number of moles of solute present in 1 kg of solvent is called:

a) Molarity
b) Molality
c) Normality
d) Formality

Answer:

b) Molality

Explanation:

Molality is defined as the number of moles of solute present in 1 kg of solvent.

8. The colligative property that is directly proportional to the number of solute particles irrespective of their nature in a solution is:

a) Osmotic pressure
b) Boiling point elevation
c) Freezing point depression
d) All of the above

Answer:

d) All of the above

Explanation:

All colligative properties are determined by the number of solute particles and are independent of their nature.

9. Van't Hoff factor (i) for urea (NH2CONH2) in aqueous solution is:

a) 1
b) 2
c) 3
d) 4

Answer:

a) 1

Explanation:

Urea is a non-electrolyte and does not dissociate in water. Thus, its Van't Hoff factor is 1.

10. A 1 molal solution of a non-volatile solute in a solvent shows a freezing point depression of 2K. If the freezing point depression constant (Kf) of the solvent is 2 K kg/mol, the Van't Hoff factor (i) for the solute is:

a) 0.5
b) 1
c) 2
d) 4

Answer:

c) 2

Explanation:

ΔTf = i × Kf × m. Given ΔTf = 2K, Kf = 2 K kg/mol, and m = 1 mol/kg. Substituting the values, we get i = 2.

11. The process of separating the components of a solution based on their different boiling points is called:

a) Sublimation
b) Distillation
c) Filtration
d) Chromatography

Answer:

b) Distillation

Explanation:

Distillation is a technique used to separate mixtures based on differences in boiling points of components.

12. When the solute particles are larger than simple molecules but are too small to be seen under the microscope, the solution is called:

a) True solution
b) Colloidal solution
c) Suspension
d) Gel

Answer:

b) Colloidal solution

Explanation:

Colloidal solutions contain particles larger than true solutions but smaller than suspensions, which are not visible to the naked eye but can be seen under a microscope.

13. In a 0.5 M solution of Na2SO4, the concentration of Na+ ions is:

a) 0.25 M
b) 0.5 M
c) 1.0 M
d) 2.0 M

Answer:

c) 1.0 M

Explanation:

Each molecule of Na2SO4 produces 2 Na+ ions. Therefore, the concentration of Na+ ions is twice that of Na2SO4.

14. An increase in temperature usually causes the solubility of solids in liquids to:

a) Increase
b) Decrease
c) Remain the same
d) Become unpredictable

Answer:

a) Increase

Explanation:

Generally, as the temperature increases, the solubility of solids in liquids also increases.

15. Which among the following will not affect the rate of dissolution of a solid solute in a liquid solvent?

a) Surface area of the solute
b) Temperature of the solution
c) Amount of solute already dissolved
d) Color of the solute

Answer:

d) Color of the solute

Explanation:

The rate of dissolution is affected by factors like surface area, temperature, and concentration, but not by the color of the solute.

16. Raising the temperature of a gas will ________ its solubility in a liquid.

a) Increase
b) Decrease
c) Not affect
d) Double

Answer:

b) Decrease

Explanation:

The solubility of gases in liquids generally decreases with an increase in temperature.

17. Which of the following solutions will have the highest boiling point?

a) 0.1 M NaCl
b) 0.1 M C6H12O6 (glucose)
c) 0.1 M CaCl2
d) 0.1 M CH3OH (methanol)

Answer:

c) 0.1 M CaCl2

Explanation:

CaCl2 dissociates to produce three ions (Ca2+ and 2 Cl−). Thus, it will have the highest boiling point due to its highest effective particle concentration.

18. The Tyndall effect is observed in:

a) True solutions
b) Colloidal solutions
c) Both true and colloidal solutions
d) Neither true nor colloidal solutions

Answer:

b) Colloidal solutions

Explanation:

The Tyndall effect is the scattering of light by particles in a colloidal solution, making the light beam visible.

19. Osmosis is the movement of:

a) Solvent molecules from a region of higher concentration to a region of lower concentration
b) Solute molecules from a region of lower concentration to a region of higher concentration
c) Solvent molecules from a region of lower concentration to a region of higher concentration
d) Solute molecules from a region of higher concentration to a region of lower concentration

Answer:

c) Solvent molecules from a region of lower concentration to a region of higher concentration

Explanation:

Osmosis is the movement of solvent molecules across a semipermeable membrane from a dilute solution to a concentrated solution.

20. Which of the following is NOT a colligative property?

a) Boiling point elevation
b) Freezing point depression
c) Osmotic pressure
d) Color

Answer:

d) Color

Explanation:

Colligative properties depend on the number of solute particles and not on their nature. Color is not a colligative property.

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