Which of the following best describes a chemical property of a pure substance?

• A. Its density
• B. Its color
• C. Its melting point
• D. Its ability to react with oxygen to form new substances

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 the options given: density, color, melting point, and ability to react with oxygen to form new substances.
3. Recognize that density, color, and melting point are physical properties because they do not involve changing the substance into something new.
4. Identify that the ability to react with oxygen to form new substances involves a chemical change, meaning the original substance transforms into different substances.
5. Conclude that the best description of a chemical property is the ability to react with oxygen to form new substances, as it reflects the substance's potential to undergo a chemical reaction.