Which of the following is an example of a chemical property of an element?

• A. Copper has a reddish-brown color.
• B. Aluminum has a density of 2.70 g/cm^3.
• C. Iron reacts with oxygen to form rust.
• D. Gold is malleable.

Answer: (C)

Verified step by step guidance

1. Understand the difference between physical and chemical properties: Physical properties can be observed or measured without changing the substance's identity, while chemical properties describe a substance's ability to undergo chemical changes and form new substances.
2. Review each option and classify it as a physical or chemical property:
3. - Copper has a reddish-brown color: This describes color, a physical property.
4. - Aluminum has a density of 2.70 g/cm^3: Density is a physical property because it involves mass and volume without changing the substance.
5. - Iron reacts with oxygen to form rust: This describes a chemical reaction where iron changes into a new substance (rust), so it is a chemical property.