1. Melting ice: Ice (solid water) changes into liquid water, but the chemical composition (H₂O) remains the same.

2. Cutting paper: Cutting paper changes its shape and size, but it remains the same chemical substance (cellulose).

3. Boiling water: Boiling water turns it into steam (a gas), but the chemical composition (H₂O) stays the same.

4. Crushing a can: Crushing a can changes its shape, but the aluminum metal it is made from remains the same.