When salt dissolves in water, a physical change occurs. This is because the salt (sodium chloride) separates into its individual ions, sodium (Na+) and chloride (Cl–), and becomes evenly distributed throughout the water. The chemical composition of the salt remains unchanged; it simply disperses in the solvent.
This process is reversible. If you were to evaporate the water, the salt would re-form, proving that the original substance has not been altered in its chemical identity. The interaction between the salt and the water molecules is what facilitates this process, highlighting the characteristics of soluble substances in a solvent.