Questions About Colloids
Multiple-Choice Questions – Colloids
1. What best describes a colloid?
A) A homogeneous mixture with large particles
B) A pure substance with ionic bonds
C) A heterogeneous mixture with intermediate particle size
D) A solution of gases
E) A compound dissolved in a solvent
2. Which of the following is an example of a colloid?
A) Saltwater
B) Smoke
C) Sand and water
D) Copper metal
E) Distilled water
3. What is the typical particle size in a colloid?
A) Less than 1 nm
B) 1–100 nm
C) 100–1000 nm
D) Over 1000 nm
E) Over 1 mm
4. What property makes colloids different from solutions?
A) Homogeneous composition
B) Permanent settling of particles
C) Scattering of light (Tyndall effect)
D) Metallic luster
E) No interactions with light
5. Which test helps identify a colloid?
A) Litmus test
B) Chromatography
C) Benedict’s test
D) Tyndall effect
E) pH test
6. Which of the following is not a type of colloid?
A) Foam
B) Emulsion
C) Solution
D) Aerosol
E) Gel
7. Which of the following is a liquid dispersed in a liquid?
A) Foam
B) Emulsion
C) Gel
D) Aerosol
E) Sol
8. In a colloid, what prevents the particles from settling?
A) Chemical bonding
B) Strong magnetic forces
C) Brownian motion
D) Covalent bonding
E) Filtration
9. What is milk classified as?
A) Solution
B) Suspension
C) Colloid (emulsion)
D) Pure substance
E) Ionic compound
10. Which of the following best describes an aerosol?
A) Gas dispersed in liquid
B) Solid dispersed in liquid
C) Liquid dispersed in gas
D) Solid dissolved in gas
E) Solid suspended in liquid
11. Why don’t colloidal particles settle like suspensions?
A) They are soluble
B) They are charged and undergo Brownian motion
C) They are too dense
D) They evaporate
E) They react chemically with the solvent
12. What happens when you shine a beam of light through a colloid?
A) No visible effect
B) Light bends
C) Light is absorbed
D) Light is scattered (Tyndall effect)
E) Light reflects completely
13. Which of the following is a solid sol colloid?
A) Paint
B) Butter
C) Fog
D) Cheese
E) Whipped cream
14. What type of colloid is fog?
A) Solid sol
B) Emulsion
C) Foam
D) Aerosol (liquid in gas)
E) Sol
15. What is the continuous phase in a colloid?
A) The dispersed phase
B) The more reactive substance
C) The medium in which particles are spread
D) The precipitate
E) The visible solid
16. What is the dispersed phase in a colloid?
A) The solvent
B) The gas
C) The phase present in larger quantity
D) The phase spread throughout the medium
E) The continuous medium
17. Which method does not separate a colloid easily?
A) Centrifugation
B) Coagulation
C) Filtration
D) Dialysis
E) All of the above separate colloids
18. Which of the following is a foam colloid?
A) Gelatin
B) Smoke
C) Whipped cream
D) Cheese
E) Paint
19. Which of the following is a lyophilic colloid?
A) Ferric hydroxide in water
B) Milk
C) Gold sol
D) Gum in water
E) Smoke
20. What can cause colloidal particles to aggregate and settle?
A) Brownian motion
B) Application of heat
C) Electrical charge neutralization (coagulation)
D) Low light conditions
E) Increasing pressure
- Questions About Electrolytes and Nonelectrolytes
- Questions on Dissociation Equations
- Questions About Suspensions
Answer Key with Explanations
1. C – Colloids are heterogeneous with intermediate particles (1–100 nm) that don’t settle.
2. B – Smoke is a colloid (solid particles dispersed in gas).
3. B – Colloidal particles range between 1–100 nanometers.
4. C – Colloids scatter light due to particle size → Tyndall effect.
5. D – The Tyndall effect helps distinguish colloids from solutions.
6. C – A solution is not a colloid; others are all colloidal types.
7. B – An emulsion is a colloid of liquid in liquid (e.g., milk).
8. C – Brownian motion keeps particles suspended in a colloid.
9. C – Milk is an emulsion, a type of colloid (liquid in liquid).
10. C – An aerosol is liquid dispersed in gas (e.g., fog).
11. B – Colloidal particles are small, charged, and move randomly.
12. D – Light is scattered, not absorbed or refracted → Tyndall effect.
13. A – Paint is a solid sol – solid dispersed in a liquid.
14. D – Fog is liquid droplets in gas, a classic aerosol.
15. C – The continuous phase is the medium where particles are dispersed.
16. D – The dispersed phase is the substance spread in the continuous phase.
17. C – Filtration cannot separate colloids due to small particle size.
18. C – Whipped cream is a foam – gas dispersed in liquid.
19. D – Gum in water forms a lyophilic (solvent-loving) colloid.
20. C – Coagulation (charge neutralization) causes aggregation and settling.
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