* No new substances are formed: When salt (NaCl) or sugar (C12H22O11) dissolves in water, the individual molecules of salt or sugar become surrounded by water molecules. They don't change their chemical composition. You can still recover the original salt or sugar by evaporating the water.
* The change is reversible: You can easily reverse the process by letting the water evaporate. The salt or sugar will be left behind, unchanged.
Contrast this with a chemical change:
* New substances are formed: For example, burning wood is a chemical change. The wood reacts with oxygen, and new substances like ash, carbon dioxide, and water are created.
* The change is not easily reversible: You can't easily get the wood back from the ash and other products.
In summary: Dissolving salt or sugar in water is a physical change because it involves a change in state or form but not a change in the chemical composition of the substances involved.
