The process of accumulation of molecular species at the surface of solid or liquid is called adsorption. It may be physisorption or chemisorption. Low temperature is favourable for physisorption. Amount of gas adsorbed by a solid depends upon nature of gas. Easily liquefiable gases are readily adsorbed. Catalyst increases the rate of reaction. Catalysis may be homogeneous or heterogeneous. Enzymes are biological catalysts. They work at optimum pH and temperature. Solutions are of three types i.e. true solutions, colloids and suspensions. Depending on the interaction between dispersed phase and dispersion medium colloids may be Lyophilic and Lyophobic. Depending on type of particles there may be multimolecular, macro-molecular and associated colloids. Sol, gel, emulsions are also various types of colloids.
Match List I with List II
|
LIST I |
LIST II |
| A. Multimolecular colloid | I. Starch sol |
| B. Macromolecular colloid | II. Gold sol |
| C. Emulsion | III. Polythene |
| D. Lyophilic colloid | IV. Vanishing cream |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A-II, B-III, C-IV, D-I
Colloids are classified by the type of particles of the dispersed phase (multimolecular, macromolecular, associated), by the interaction between the dispersed phase and the medium (lyophilic, lyophobic) and by the physical states of the two phases (sol, gel, emulsion).
(A) Multimolecular colloid — This matches (II) Gold sol. In a multimolecular colloid many atoms or small molecules aggregate into particles of colloidal size; a gold sol contains particles made of many gold atoms.
(B) Macromolecular colloid — This matches (III) Polythene. Macromolecules in a suitable solvent are themselves of colloidal size; the man-made macromolecules named in the book are polythene, nylon, polystyrene and synthetic rubber.
(C) Emulsion — This matches (IV) Vanishing cream. An emulsion is a liquid dispersed in a liquid; vanishing cream (like milk) is an oil-in-water emulsion.
(D) Lyophilic colloid — This matches (I) Starch sol. Sols formed directly by mixing substances like gum, gelatine and starch with a suitable liquid are lyophilic (solvent-loving) and reversible.
Note 1: Item (I) Starch sol fits two entries of List-I: starch is a natural macromolecule, so starch sol is a macromolecular colloid as well as a lyophilic colloid. Only polythene (III) fits (B), so (D)-(I).
Note 2: 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.