Which of the following is an example of a surfactant?

A surfactant, or surface-active agent, is a substance that reduces the surface tension of a liquid, allowing it to spread more easily. Surfactants are often amphiphilic molecules, meaning they have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts. This dual nature allows them to interact with both oil and water, making them particularly effective in cleaning applications.

Soap is a classic example of a surfactant, as it contains long hydrocarbon chains that are hydrophobic and a polar head group that is hydrophilic. When soap is added to water, the hydrophobic tails of the soap molecules attach themselves to grease or oil, while the hydrophilic heads remain in the water. This interaction helps to lift and disperse the grease, allowing it to be washed away.

In contrast, sodium chloride, glucose, and hydrochloric acid do not possess surfactant properties. Sodium chloride is a simple ionic compound that dissolves in water but does not affect surface tension in the way surfactants do. Glucose is a standard carbohydrate that is soluble in water but does not have the amphiphilic structure necessary for surfactant action. Hydrochloric acid is a strong acid that