What is the difference between adhesion, cohesion and surface tension? Which would be used in a xylem? Which would enable an insect to sit on water?

Cohesion, adhesion and surface tension are different from each other. Adhesion is used in xylem. Surface tension enables an insect to sit on water.

Explanation:

The force of attraction between the molecules of the same type is called cohesion. The force of attraction between the molecules of different type is called adhesion. Tendency of fluid surfaces to shrink to minimum possible area due to the attraction between the liquid molecules is called surface tension.

Adhesion is used in xylem. In xylem water molecules move from the roots to different parts of the plant through the xylem tubes. The adhesive force between the water molecules and xylem walls make the movement of water possible.

Surface tension enables an insect to sit on the surface of a liquid. Due to surface tension the water surface stretches like a membrane due to the higher attractive force between the water molecules.