What does the head of a shampoo molecule do?

• A. Repels water and attracts oil
• B. Attracts water and oil
• C. Neutral, no attraction or repulsion
• D. Attracts water and repels oil and grease

Answer: (D)

The main idea is how a surfactant works in shampoo. A shampoo molecule has a water-loving head (hydrophilic) and a tail that loves oil (hydrophobic). The head is attracted to water, so it stays in the watery part of the shampoo solution and helps keep the molecule soluble. The tail, which is attracted to oil and grease, moves into those oily particles on the hair. When many molecules act together, they form structures where the tails are drawn into the oil and the heads face the water, creating micelles. This arrangement lets oils and dirt be lifted off the hair and carried away by water during rinsing. So the head’s job is to attract water and stay with the watery phase, while it repels oil and grease, enabling the cleansing action.