1. Observation and Reversibility:

* Dissolving: When you add salt to water, it disappears into the solution. This might seem like a chemical change, but it's actually just the salt crystals breaking apart and dispersing.

* Evaporation: If you heat the saltwater solution, the water will evaporate, leaving the salt crystals behind. This demonstrates that the salt hasn't been permanently altered. The salt is simply separated from the water.

2. No New Substance Formation:

* Composition: Salt (NaCl) is still salt (NaCl) even when dissolved in water. You haven't created any new chemical compounds.

* Chemical Properties: The salt retains its original chemical properties. It still has the same chemical bonds, and it can be recovered by evaporation.

3. Energy Changes:

* Dissolving is often endothermic: While not always noticeable, the dissolving process can absorb a small amount of heat, but this is not a chemical reaction.

* No significant energy release: There is no significant release of heat or light that would indicate a chemical reaction.

Key Points:

* Physical changes involve alterations in the form or appearance of a substance, but not its chemical composition.

* Chemical changes result in the formation of new substances with different chemical compositions.

In summary: Dissolving table salt in water is a physical change because:

* The salt is simply dispersed in the water, not chemically altered.

* The original components (salt and water) can be easily recovered by evaporation.

* No new substance is formed.