Which of the following is a necessary condition for capillary action to take place in a narrow tube kept in a liquid?

The correct answer is option 1) i.e. Adhesive forces must be greater than the cohesive forces

CONCEPT:

• Capillary action: Capillary action is the movement of a liquid along the surface of a solid due to the attraction of molecules of the liquid to the molecules of the solid.
  • For capillary action to take place, the force between the liquid and solid must be greater than the intermolecular forces of the liquid.
  • The force between two different types of molecules are called adhesive forces and the forces within the same type of molecules are called cohesive forces.

EXPLANATION:

• Capillary action occurs only when the liquid can move along the surface of another solid. This requires adhesive forces between the liquid and solid.
• If the cohesive forces within the liquid were greater, the surface tension of the liquid increases and it will try to occupy a lesser surface area possible.
• Hence, adhesive forces must be greater than the cohesive forces for capillary action to take place.