Which of the following is a chemical property of iron?

• A. Iron is silver-gray in color.
• B. Iron has a density of 7.87 g/cm^3.
• C. Iron is malleable.
• D. Iron reacts with oxygen to form rust.

Answer: (D)

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.
2. Review each option and classify it as physical or chemical: Color, density, and malleability are physical properties because they describe appearance, mass per volume, and ability to be shaped without changing composition.
3. Identify the option that involves a chemical change: Reacting with oxygen to form rust involves a chemical reaction where iron's composition changes, indicating a chemical property.
4. Conclude that the chemical property of iron is its ability to react with oxygen to form rust, as this describes how iron behaves in a chemical reaction.
5. Remember that chemical properties are often observed during or after a chemical reaction, unlike physical properties which can be observed without altering the substance.