* No new substances are formed: The salt (NaCl) and water (H₂O) molecules simply mix together. They don't chemically react to create something entirely new.

* The change is reversible: You can easily separate the salt from the water by evaporating the water, leaving the salt behind. This means the original substances are still present.

* The chemical composition of the salt and water remains unchanged: The sodium (Na) and chlorine (Cl) atoms in the salt, and the hydrogen (H) and oxygen (O) atoms in the water, retain their original bonds and properties.

In contrast, a chemical change involves the formation of new substances with different properties. Examples of chemical changes include burning wood or baking a cake.