Surface Tension – Ability of a Liquid Surface to Resist Tension Statement: The property of a liquid that enables its free surface to resist a tensile stress (pulling apart) is called surface tension.

Introduction:
Surface tension quantifies the energetic cost of increasing liquid surface area. It manifests as a membrane-like behavior that resists stretching, affecting droplets, bubbles, capillarity, and wetting.

Given Data / Assumptions:

• Clean liquid–gas interface at equilibrium.
• Isothermal conditions; negligible contamination.
• No surfactants unless stated.

Concept / Approach:

Surface tension has units of force per unit length or energy per unit area. Molecules at the surface experience net inward cohesive forces, creating a tendency to minimize area and resist tensile deformation of the interface.

Step-by-Step Solution:

Verification / Alternative check:

Experiments such as ring/plate tensiometry directly measure the force needed to detach or expand a liquid surface.

Why Other Options Are Wrong:

Disagree: Contradicts the physical definition. Statements about solids, vacuum, or viscosity are irrelevant to the interfacial property being defined.

Common Pitfalls:

Confusing surface tension with viscosity; assuming it acts in the bulk rather than at the interface; overlooking surfactant effects that reduce surface tension.

Final Answer:

Agree