Which term describes materials used to increase a liquid's ability to moisten a solid by lowering surface tension?

Which term describes materials used to increase a liquid's ability to moisten a solid by lowering surface tension?

• A. Detergents
• B. Surfactant
• C. Emulsifier
• D. Wetting agents

Answer: (D)

Wetting happens when a liquid spreads over a solid surface. Materials that lower the surface tension at the liquid–solid interface make the liquid spread more easily, reducing the contact angle and improving moistening. Wetting agents are exactly those substances designed to enhance this spreading by altering interfacial tensions, so the liquid can cover the solid more thoroughly. Surfactants like detergents or emulsifiers can also reduce surface tension, but the term that directly describes the agents that boost a liquid’s ability to moisten a solid by lowering surface tension is wetting agents, which is why this option fits best.

Wetting happens when a liquid spreads over a solid surface. Materials that lower the surface tension at the liquid–solid interface make the liquid spread more easily, reducing the contact angle and improving moistening. Wetting agents are exactly those substances designed to enhance this spreading by altering interfacial tensions, so the liquid can cover the solid more thoroughly. Surfactants like detergents or emulsifiers can also reduce surface tension, but the term that directly describes the agents that boost a liquid’s ability to moisten a solid by lowering surface tension is wetting agents, which is why this option fits best.