* Melting ice: This is a change of state from solid to liquid, but the chemical composition (H₂O) remains the same.
* Boiling water: Similar to melting, this is a change of state from liquid to gas, but the chemical composition remains unchanged.
* Cutting paper: This is a physical change in size and shape, but the paper's chemical makeup stays the same.
* Mixing salt and water: While the salt dissolves, it doesn't chemically react with the water. You can still separate the salt by evaporation.
* Crushing a rock: This is a physical change that alters the size and shape of the rock, but its chemical composition stays the same.
Key takeaway: If a substance changes its form but not its chemical composition, it's a physical change.
