Which option lists nonionic surfactants?

• A. Bacterial Agents
• B. Sodium Lauryl Sulfate
• C. Sorbitan Esters, Polyoxyethylene Derivatives
• D. Gelatin, Egg Yolk

Answer: (C)

Nonionic surfactants have neutral, non-ionizing head groups. Their surface activity comes from a hydrophobic tail paired with a polar head that does not carry a charge in solution. Sorbitan esters and their polyoxyethylene derivatives fit this pattern: the Span and Tween series are based on sorbitan esters, and adding polyoxyethylene chains creates a hydrophilic, neutral head. Because the head groups do not ionize, these are classified as nonionic surfactants and are widely used as emulsifiers.

Sodium lauryl sulfate is an example of an ionic surfactant (anionic), due to the charged sulfate group. Gelatin and egg yolk are protein-based emulsifiers rather than small-molecule surfactants with a defined nonionic head. Biosurfactants from bacteria can vary in charge, but they are not a defined nonionic class like sorbitan esters with polyoxyethylene.