A colloid is a heterogeneous system in which one substance is dispersed as very fine particles in another substance. Their range of diameters is between 1-1000 nm. Based on dispersed phase and dispersion medium, colloids may be of different types like sol, gel, emulsion, aerosol, foam etc. Based on nature of interaction between two phases, sols are divided into Lyophilic and Lyophobic sols. Colloidal solutions exhibit various properties like Tyndall effect, Brownian movement and Electrophoresis. Stability of colloids is due to presence of charge. If somehow charge is removed, the particles will coagulate. Coagulation rate by various solutions containing ions, is decided by Hardy-Schulze rule. Everyday we come across many colloids. The meals we eat, clothes we wear, wooden furniture etc. are largely composed of colloids.
Match List I with List II
| List I | List II |
| A. Aerosol | I. Soap lather |
| B. Gel | II. Butter |
| C. Emulsion | III. Cheese |
| D. Foam | IV. Mist |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-IV, B-III, C-II, D-I
Colloids are named by the physical state of the dispersed phase and of the dispersion medium.
A. Aerosol — This matches IV. Mist. An aerosol has a liquid or solid dispersed in a gas; mist, fog and cloud are liquid droplets in air.
B. Gel — This matches III. Cheese. A gel has a liquid dispersed in a solid; cheese and jellies are gels.
C. Emulsion — This matches II. Butter. An emulsion has a liquid dispersed in another liquid; butter is a water-in-oil (W/O) emulsion, milk an oil-in-water one.
D. Foam — This matches I. Soap lather. A foam has a gas dispersed in a liquid; soap lather, froth and whipped cream are foams.
Shortcut: A-IV and D-I appear in Options (2) and (4); cheese is a gel (B-III), which leaves Option (4).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Types of Colloidal Systems (rows of Table 5.4)
| Dispersed phase | Dispersion medium | Type of colloid | Examples |
|---|---|---|---|
| Liquid | Solid | Gel | Cheese, butter, jellies |
| Liquid | Liquid | Emulsion | Milk, hair cream |
| Liquid | Gas | Aerosol | Fog, mist, cloud, insecticide sprays |
| Gas | Liquid | Foam | Froth, whipped cream, soap lather |
Emulsions – “… There are two types of emulsions. (i) Oil dispersed in water (O/W type) and (ii) Water dispersed in oil (W/O type). In the first system, water acts as dispersion medium. Examples of this type of emulsion are milk and vanishing cream. In milk, liquid fat is dispersed in water. In the second system, oil acts as dispersion medium. Common examples of this type are butter and cream.”