Enthalpy change resulting, when unit mass of solid is wetted with sufficient liquid, so that further addition of liquid produces no additional thermal effect, is called the heat of

The correct answer is:

C. Wetting

Explanation:

Heat of wetting is defined as the enthalpy change when a unit mass of solid is wetted by enough liquid so that adding more liquid produces no further heat effect.

It is the thermal effect associated with the interaction between the solid surface and the liquid during initial wetting.

Other options:

A. Mixing: Heat change due to mixing of two substances.

B. Adsorption: Heat change due to adsorption of molecules on a surface.

D. Complete wetting: Describes a physical phenomenon (contact angle = 0°), not an enthalpy change.

Final answer: C. Wetting