AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
The outer surface of a micelle is covered with ionic (hydrophilic) ends of soap molecules, which cause ion-ion repulsion between micelles, preventing them from coming together and precipitating.
Source: Chapter 4, Section 4.5 – Soaps and Detergents
---
The key phrase from the passage is: "The micelles stay in solution as a colloid and will not come together to precipitate because of ion-ion repulsion." Examiners expect you to identify the ionic/hydrophilic outer surface and link it directly to ion-ion repulsion as the cause of colloidal stability. Mentioning only "hydrophilic" without the repulsion mechanism may lose the mark.