Which term means the attractive force between molecules of the same substance?

Which term means the attractive force between molecules of the same substance?

• A. Adhesion
• B. Umbra
• C. Penumbra
• D. Cohesion

Answer: (D)

Cohesion is the attraction between molecules of the same substance. It explains why molecules in a drop of water stick together and how surface tension forms at the air-water interface. Adhesion, by contrast, is the attraction between different substances—like water sticking to glass. The remaining terms relate to shadows, not molecular forces, so they don’t describe how like molecules attract one another.

Cohesion is the attraction between molecules of the same substance. It explains why molecules in a drop of water stick together and how surface tension forms at the air-water interface. Adhesion, by contrast, is the attraction between different substances—like water sticking to glass. The remaining terms relate to shadows, not molecular forces, so they don’t describe how like molecules attract one another.