NEET Chemistry: Colloidal Chemistry questions with solutions

Q1. Freshly prepared precipitate sometimes gets converted to colloidal solution by:

1. coagulation
2. electrolysis
3. diffusion
4. peptisation

Answer: peptisation

Peptisation is the conversion of a freshly formed precipitate into a colloidal sol by adding a suitable peptizing agent. The agent adsorbs on the precipitate particles, giving them charge and preventing aggregation.

Q2. On adding few drops of dilute \( H C l \) or \( \boldsymbol{F} \boldsymbol{e} \boldsymbol{C l}_{3} \) to freshly precipitated ferric hydroxide, a red coloured colloidal solution is obtained. This phenomenon is known as:

1. peptization
2. dialysiss
3. protection
4. dissolution

Answer: peptization

The red colloidal solution forms when freshly precipitated ferric hydroxide is dispersed into colloidal particles by dilute HCl or FeCl3. This conversion of a precipitate into a colloid is called peptization.