Question

On the surface of the liquid in equilibrium, molecules of the liquid possess:

• A. maximum potential energy
• B. minimum potential energy
• C. maximum kinetic energy
• D. minimum kinetic energy

Answer 1

Answer: (A)

maximum potential energy

At liquid-air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). The net effect is an inward force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. Thus, the surface becomes under tension from the imbalanced forces. These imbalanced forces have the greatest value on the surface compared to the other points in the liquid.

Thus the maximum potential energy is possessed by liquid on its surface.