Answer: The force acting per unit length on the liquid surface.
- A The resistance of a liquid to flow in standard practice
- B The force acting per unit length on the liquid surface
- C The pressure exerted by vapour above a liquid under most conditions encountered
- D The energy needed to boil a liquid as frequently observed in practice
Correct answer: B. The force acting per unit length on the liquid surface
Explanation: Surface tension is the force acting per unit length perpendicular to a line on the liquid surface, due to unbalanced molecular attraction at the surface.
Boyle's law: at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume (P ∝ 1/V), so the P–V plot is a hyperbola — halving the volume doubles the pressure. Image: Reginaprice2013, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Discover why gases expand to fill any container while liquids flow and solids hold their shape. Master the gas laws, the ideal gas equation, and the reasons real gases deviate from ideal behavior.