Which term defines the attractive forces between molecules within a liquid?

• A. Adhesion
• B. Viscosity
• C. Cohesion
• D. Surface tension

Answer: (C)

Cohesion is the attractive forces that hold the molecules of a liquid together. These intermolecular forces act between like molecules, giving liquids their ability to form droplets, influence how they flow, and contribute to surface phenomena. Adhesion, by contrast, is the attraction between liquid molecules and other materials, such as a liquid sticking to a glass surface. Viscosity describes how strongly a liquid resists flow, which arises from cohesive forces but is a property of flow rather than a definition of the inter-molecular forces themselves. Surface tension comes from cohesion at the liquid’s surface, creating that “skin” effect. So the term that defines the attractive forces within a liquid is cohesion.