ACS Chemistry Practice Exam 2025 – The All-in-One Guide to Exam Success!

A physical property is a characteristic of a substance that can be observed or measured without changing the substance's identity. The color of a substance is a clear example of a physical property because it can be observed directly and does not involve any chemical changes to the material.

Other options refer to chemical properties, which describe a substance's ability to undergo chemical changes or reactions. Flammability pertains to a substance's capacity to ignite and burn, indicating how it reacts under certain conditions. Reactivity with acid refers to how a substance behaves when it comes into contact with an acid, which is also a process involving chemical changes. Similarly, corrosion resistance describes how a substance withstands deterioration due to chemical reactions, often with moisture or air, indicating its behavior in chemical reactions.

Overall, the distinction lies in the fact that color is an observable quality that does not require alteration of the chemical identity of the substance, making it a definitive example of a physical property.