Chemical Engineering - Fluid Mechanics - Discussion

The reason should be the force of cohesion. It is because adhesion is the property by which things gets wet after having a contact with the liquid while surface tension makes the surface intact. Cohesion is the force responsible for surface tension and therefore it restricts the liquid from adhering with the other surfaces. Cohesion is the force among the molecules of the same matter.

The reason we consider the surface area of the entire mass of mercury, including the part of the surface that is in contact with the glass, is because mercury does not adhere at all to glass. So the surface tension of the mercury acts over its entire surface area, including where it is in contact with the glass. If instead of glass, the tube were made out of copper, the situation would be very different.

It should be force of adhesion, because force of adhesion works between two different surfaces.

Hello Sachin !

surface tension of any fluid particle acts radially over the tangential components so that the fluid particles try to obtain a minimal surface area. In this stake the mercury droplet gets spherical and thus have minimum contact just at only one point on the glass

Because the surface tension is force/length.