Cohesive force is experienced between

What is the necessary force for a water drop to stick to a glass surface?

Show that the force exerted by a fluid at rest is perpendicular to its contact surface.

Consider a liquid contained in a vessel. The liquid-solid adhesive force is very weak compared to the cohesive force in the liquid. The shape of the liquid surface near the solid shall be

$A$ drop of oil is placed on the surface of water. Which of the following statements is correct?

Explain why:
$(a)$ The angle of contact of mercury with glass is obtuse,while that of water with glass is acute.
$(b)$ Water on a clean glass surface tends to spread out while mercury on the same surface tends to form drops. (Put differently,water wets glass while mercury does not.)
$(c)$ Surface tension of a liquid is independent of the area of the surface.
$(d)$ Water with detergent dissolved in it should have small angles of contact.
$(e)$ $A$ drop of liquid under no external forces is always spherical in shape.