The process of converting a precipitate into colloidal sol is known as

The correct answer is Option (2) → Peptization

Peptization is the conversion of a freshly prepared precipitate into a colloidal sol by shaking it with the dispersion medium in the presence of a small amount of an electrolyte (the peptizing agent). The precipitate adsorbs one kind of ion of the electrolyte; its particles take up like charges, repel one another and break up into colloid-sized particles. For example, freshly precipitated \( \ce{Fe(OH)3} \) shaken with a little \( \ce{FeCl3} \) solution gives a red sol. The reverse change, sol to precipitate, is coagulation.

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):
Peptization – “Peptization may be defined as the process of converting a precipitate into colloidal sol by shaking it with dispersion medium in the presence of a small amount of electrolyte. The electrolyte used for this purpose is called peptizing agent.”