* Physical Properties: These are characteristics that can be observed or measured without changing the substance's chemical composition. Examples include color, density, melting point, boiling point, etc.

* Chemical Properties: These describe how a substance interacts with other substances. They involve changes in the chemical composition of the substance.

In the case of iron and hydrochloric acid:

* Iron (Fe) reacts with hydrochloric acid (HCl) to produce iron(II) chloride (FeCl2) and hydrogen gas (H2).

* This is a chemical change because the iron and hydrochloric acid have been transformed into new substances.

* The evolution of hydrogen gas is a clear indication of a chemical reaction.

Therefore, the reaction of iron with hydrochloric acid is a chemical property, not a physical property.