Mercury have very cohesion force which attracts its own molecules due to which it do not wet glass tube and due to this it have very high surface tension.

Cohesion: Mercury is known as a non-wetting liquid due to its high cohesion. Cohesion is the force of attraction between molecules of the same substance. In the case of mercury, the mercury molecules have a strong attraction to each other, which causes the liquid to form droplets and resist spreading on a surface.



Mercury is a unique liquid because it exhibits a phenomenon called non-wetting. This means that when mercury comes into contact with a solid surface, it does not spread out or wet the surface like most other liquids. Instead, it forms droplets that bead up on the surface.

This non-wetting property of mercury is primarily due to its high cohesion. Cohesion is the force of attraction between molecules of the same substance. In the case of mercury, the mercury molecules have a strong attraction to each other, causing them to stick together and resist spreading on a surface.

Surface tension: One of the factors contributing to cohesion is surface tension. Surface tension is the cohesive force acting on the surface molecules of a liquid. It is responsible for the formation of droplets and the resistance of liquids to spread on a surface. In the case of mercury, its high surface tension is a result of the strong cohesive forces between its molecules.

Adhesion: Adhesion is the force of attraction between molecules of different substances. While adhesion does play a role in wetting, it is not the primary factor responsible for mercury's non-wetting behavior. If adhesion were the dominant force, mercury would wet the surface and spread out, but this is not the case.

Viscosity: Viscosity is a measure of a liquid's resistance to flow. While viscosity does affect how liquids spread, it is not the primary reason for mercury's non-wetting behavior. Even though mercury has a relatively low viscosity, it still exhibits non-wetting due to its high cohesion and surface tension.

In conclusion, mercury's non-wetting behavior is primarily due to its high cohesion, which is caused by the strong attractive forces between its molecules. This cohesion results in a high surface tension, causing mercury to form droplets and resist spreading on a surface.