Question

Choose the correct answer from the given options below:
The phenomenon due to which the exposed liquid behaves like a stretched membrane is called:
A) Capillarity
B) Cohesion
C) Adhesion
D) Surface tension

Answer 1

Hint : When a liquid comes out of a package or a container, for small liquid amounts, it will form a stretched membrane at the surface. This is due to the attractive force between the water molecules that make them stick to each other rather than to spread out.

Complete step by step answer
When a liquid is exposed to the air, it behaves like a stretched membrane as the water molecules are attracted to each other. This property of liquid is also called Surface tension. Surface tension is defined as the property of liquids to behave elastically which makes it acquire the least surface area that is exposed to the surface of the atmosphere as possible.
At liquid-air interfaces, surface tension results from the attraction of water molecules to each other, which is a cohesive force, than to the molecules in the air, which is an adhesive/repulsive force. The combined effect of these two forces is an inward force at the surface of the liquid which causes the surface to behave as if it were covered with a stretched elastic membrane.
So the phenomenon due to which the exposed liquid behaves like a stretched membrane is called surface tension.
Option (D) is correct.

Note
Surface tension has the dimension of force per unit length, or energy per unit area is only defined for Newtonian liquids. While cohesion and adhesion forces play a role in the membrane formation, it is their combined effect which is called surface tension that is considered to be the cause of the formation of the stretched membrane. Capillary action is also an effect of surface tension that is only applicable to small tubes that contain liquids.