Given below are statements regarding colloids. Identify the correct statement.

The correct answer is option 3, i.e., Starch, cellulose, etc. are examples of naturally occurring macromolecular colloids.

• A colloid is a heterogeneous mixture in which one substance is dispersed (dispersed phase) as very fine particles in another substance called a dispersion medium.
• Based on the nature of the interaction between the dispersed phase and dispersed medium, the colloids are classified into Lyophilic colloids and Lyophobic colloids. Hence, Option 1 is NOT correct.
• Based on the type of particles of the dispersed phase, the colloids are classified into Multimolecular colloids, Macromolecular colloids, and Associated colloids.
• In multimolecular colloids, the particles have the size in the colloidal range of diameter < 1nm. Eg: Sulphur sol consists of particles containing thousand or more of S₈ sulphur molecules. Hence, Option 2 is NOT correct.
• Macromolecular colloids are quite stable and resemble true solutions in many respects. Starch, cellulose, proteins are naturally occurring macromolecular colloids; and polythene, nylon, etc. are the man-made macromolecules. Hence, Option 3 is correct.
• Bredig's arc method is not one of the chemical methods to prepare colloids.
  • In Bredig's arc or Electrical disintegration method, an electric arc is struck between electrodes of the metal immersed in the dispersed medium.
  • The intense heat vapourises the metal, which then condenses to form particles of colloidal size.
• The chemical methods to prepare colloids include Double decomposition, Oxidation, Reduction, and Hydrolysis. Hence, Option 4 is NOT correct.