* Physical Changes: Alter the form or appearance of a substance but don't change its chemical composition.

* Examples: Melting ice, boiling water, cutting paper.

* Chemical Changes: Result in the formation of new substances with different chemical properties.

* Examples: Burning wood, rusting metal, baking a cake.

Why heating water is physical:

* Water's composition remains the same: Hot water is still H₂O, just like cold water. The molecules themselves haven't changed.

* The change is reversible: Cooling hot water down turns it back into cold water. This reversibility is a key indicator of a physical change.

Let me know if you have any other questions!