Question

Which molecule of a liquid has higher potential energy?

• A. One at the centre of gravity of the liquid
• B. One at maximum distance from centre of gravity of liquid
• C. One in the surface film
• D. One at the bottom of the vessel

Answer 1

The correct option is C One in the surface film

Molecules at the surface feel an inward force due to strong cohesive forces then those inside the liquid because the inside molecules are surrounded by similar molecules, cohesive force acts in all directions making the net force on a single molecule equal to zero. But this is not the case with surface molecules, these molecules feels inward force, hence less stable i.e. have higher potential energy.