Evaporation of water is a physical change. This is because during evaporation, water changes from a liquid state to a gaseous state without altering its chemical composition. The molecules of water remain H2O throughout the process.
Physical changes involve changes in the state or form of a substance without any change in its chemical identity. In the case of evaporation, the water molecules gain enough energy to break free from the liquid surface and become water vapor. This process is reversible, meaning that the water vapor can condense back into liquid water under the right conditions.
In contrast, a chemical change would involve a transformation in the chemical structure of the substance, resulting in the formation of one or more new substances with different properties. Since evaporation does not involve any such transformation, it is classified as a physical change.