Why is density commonly used to identify a material?

• A. Because density is the same for all substances at room temperature.
• B. Because density depends only on the color of the material.
• C. Because density changes significantly with the amount of material present.
• D. Because density is a unique physical property for many pure substances.

Answer: (D)

Verified step by step guidance

1. Understand that density is defined as the mass of a substance divided by its volume, expressed as \(\text{density} = \frac{\text{mass}}{\text{volume}}\).
2. Recognize that density is an intrinsic physical property, meaning it does not depend on the amount of material present but rather on the nature of the substance itself.
3. Note that many pure substances have characteristic densities that remain constant under specific conditions (such as room temperature and pressure), making density a reliable identifier.
4. Contrast density with properties like color or size, which can vary or be less distinctive, whereas density provides a quantitative measure unique to the material's composition and structure.
5. Conclude that because density is unique and consistent for many pure substances, it is commonly used to identify and distinguish materials in chemistry and material science.