Question

Which of the following forms cationic micelles above certain concentration?

• A. Sodium dodecyl sulphonate
• B. Sodium acetate
• C. Urea
• D. Cetyl trimethyl ammonium bromide

Answer 1

Answer: (D)

Cetyl trimethyl ammonium bromide forms cationic micelles above a certain concentration. In the molecule of detergents and soap, the negative ions aggregate to form a micelle of colloidal size. In polar medium (like water), the negative ion has a long hydrocarbon chain and a polar group$(-CO{O}^{-})$ at one end and on other end, it has $N^{+}$ ion, thus cationic micelle is formed.