Which statement best describes cohesion in fluids?

Cohesion in fluids is best described as the attraction between similar molecules. This property arises from intermolecular forces, such as hydrogen bonds or van der Waals forces, which hold the same type of molecules together. A prime example of this phenomenon is seen in water, where the molecules are attracted to each other, resulting in behaviors like surface tension. This cohesive force is significant because it can influence the movement of fluids and the formation of bubbles or droplets.

The other statements refer to different concepts. The attraction between different substances pertains to adhesion, which describes how different types of molecules interact. The resistance of a fluid to flow is related to viscosity, a distinct property from cohesion. Lastly, the pressure exerted by a fluid in motion concerns fluid dynamics and is defined in terms of velocity and density, not directly related to the cohesive properties of the fluid itself. Understanding these definitions helps clarify the unique role that cohesion plays in fluid mechanics.