Answer: Their hydrophilic part carries a positively charged nitrogen atom instead of a negative sulphonate group.
- A They have a noticeably shorter hydrophobic hydrocarbon chain attached to their polar head group under usual circumstances
- B Their hydrophilic part carries a positively charged nitrogen atom instead of a negative sulphonate group
- C They are built mainly from sugar-based carbohydrate units rather than long hydrocarbon chains according to most studies
- D They mix poorly with water and instead form micelles mainly within non-polar oils in the majority of documented cases
Correct answer: B. Their hydrophilic part carries a positively charged nitrogen atom instead of a negative sulphonate group
Explanation: Cationic detergents have a quaternary ammonium group with a positive charge as the hydrophilic part, unlike anionic detergents whose hydrophilic head carries a negative charge.
The hydrophobic hydrocarbon tail of each soap/detergent molecule dissolves into an oily dirt droplet, while the hydrophilic (ionic) head stays in the surrounding water - trapping the grease inside a micelle that rinses away with water.
Concept context
Drugs and how they interact with biological targets, chemicals in food, and cleansing agents (soaps and detergents) - chemistry applied directly to daily life and healthcare.