Chemistry Regents Practice Test

At STP, which physical property of aluminum remains constant from sample to sample?

1. Mass

2. Volume

3. Density

4. Temperature

The correct answer is: Density

Density is a characteristic physical property of a substance that is defined as its mass per unit volume. For a pure substance like aluminum, density remains consistent across different samples, assuming the samples are at the same conditions, such as standard temperature and pressure (STP). Aluminum has a specific density value, approximately 2.70 grams per cubic centimeter, which does not change irrespective of the quantity or shape of the aluminum sample. Mass and volume can vary significantly between different samples of aluminum, depending on the size and quantity of the material. Temperature, while it can remain constant under specific conditions, is not an intrinsic property of the material itself, as it can fluctuate based on environmental influences. Thus, the stability of density under the standardized conditions of STP makes it the correct choice for this question.