What property of a liquid allows it to resist external forces due to molecular cohesion?

The ability of a liquid to resist external forces due to molecular cohesion is known as surface tension. Surface tension arises from the cohesive forces between liquid molecules; these forces are stronger at the surface due to the molecules being pulled inward by neighboring molecules beneath them. This unique property allows the surface of the liquid to behave as if it is covered by a thin elastic film, which is why small amounts of liquid can form droplets or why some insects can walk on water without sinking.

Other options, while they may relate to liquid properties, do not specifically address the phenomenon of resisting external forces in the same way. Viscosity refers to a liquid’s resistance to flow, which is related to its internal friction rather than surface phenomena. Density describes the mass per volume of a substance and does not directly relate to the cohesive forces at the surface of a liquid. Capillarity, on the other hand, involves the movement of liquid through narrow spaces due to adhesive and cohesive forces but is not primarily focused on resisting external forces. Thus, surface tension is the appropriate term for the property in question.