Which of the following are examples of cationic surfactants?

• A. Bacterial Agents
• B. Soaps and Sulfonates
• C. Sorbitan Esters
• D. Acacia

Answer: (A)

Cationic surfactants are positively charged surface-active agents, usually quaternary ammonium compounds. The positive charge helps them interact with the negatively charged surfaces of microbial cells, which is why they’re often used as disinfectants and antiseptics.

Soaps and sulfonates are anionic surfactants because they carry a negative charge. Sorbitan esters are nonionic; they provide surface activity without any charge. Acacia is a natural gum used as a thickener or stabilizer, not a surfactant. “Bacterial agents” don’t describe a surfactant class at all; they refer to substances that act on bacteria rather than molecules that reduce surface tension.

If you were to name true cationic surfactants, you’d think of quaternary ammonium compounds like benzalkonium chloride or cetyltrimethylammonium bromide.