What is surface tension in liquids?

Surface tension in liquids is best described as a cohesive force creating a thin elastic membrane at the liquid's surface. This phenomenon occurs due to the attractive forces between molecules within the liquid. Molecules at the surface experience a net inward force because they are surrounded by other liquid molecules on the sides and below but lack similar interactions above, leading to a minimized surface area and the formation of a "membrane-like" effect.

Surface tension is crucial in various applications and phenomena, such as water droplets forming beads on a surface, the ability of small insects to walk on water, and the functioning of capillary action in plants. This cohesive property is fundamentally linked to molecular interactions and is not affected by temperature in the context of defining surface tension itself, which rules out the option related to temperature. The other choices regarding liquid purity and electrical conductivity are unrelated aspects of liquid behavior and do not pertain to the concept of surface tension.