* Chemical change: Involves the formation of new substances with different chemical properties. The original substance is broken down into different substances.

* Physical change: Changes the form or appearance of a substance but not its chemical composition.

Example of Decomposition:

When you decompose a substance like hydrogen peroxide (H₂O₂), it breaks down into water (H₂O) and oxygen gas (O₂). The chemical composition of the original substance has changed.

Key Indicators of a Chemical Change:

* Formation of a new substance: The products are different from the original substance.

* Change in color: A new substance often has a different color.

* Gas production: Bubbles may form indicating the release of a gas.

* Heat or light production: Energy changes can occur during a chemical reaction.

Let me know if you'd like more examples!