Question

There is a depression in the surface area of a liquid in a capillary when-

a) The cohesive force is smaller than adhesive
b) The cohesive force is greater than adhesive
c) They are equal
d) None of these

Answer 1

a) the cohesive force is smaller than the adhesive force

Here a depression is formed on the surface as the liquid creeps up the sides of the capillary and holds its position (the molecules of the liquid sticks to the molecules of the capillary due to its adhesive force) however the cohesive force within the molecules of the liquid is not strong enough to pull these molecules toward itself to form a sphere.

If the cohesive force within the molecules of the liquid were greater then they would form a drop like structure