* Chemical Change: Involves the formation of new substances with different chemical properties.

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

When zinc reacts with an acid (like hydrochloric acid), the following happens:

1. Zinc atoms lose electrons, forming zinc ions (Zn²⁺).

2. Hydrogen ions from the acid gain electrons, forming hydrogen gas (H₂).

This process involves the breaking and forming of chemical bonds, resulting in entirely new substances (zinc ions and hydrogen gas) with properties different from the original zinc and acid.

Key Indicators of a Chemical Change:

* Gas production: You observe the formation of bubbles (hydrogen gas) in this reaction.

* Change in color: The solution may change color.

* Heat or light production: The reaction often releases heat.

Therefore, the reaction between zinc and acid is a chemical change.