Question

how can you tell if a physical change has occurred? the composition of the substance has not changed. the change cannot be reversed. the change creates a new object.

Explanation:

In a physical change, the substance's chemical composition remains the same. A physical change like melting ice just changes the state from solid to liquid without altering the water - molecule composition. Reversibility is not a defining factor (some physical changes are irreversible like breaking glass), and creating a new object usually implies a chemical change.

Answer:

The composition of the substance has not changed.