Which statement about density is true?

• A. Density is defined as mass divided by volume.
• B. Density increases as the volume of a substance increases, assuming mass stays constant.
• C. The SI unit of density is kilogram per meter.
• D. Two substances with the same mass must have the same density.

Answer: (A)

Verified step by step guidance

1. Recall the definition of density, which is a physical property of matter that relates mass to volume.
2. Write the formula for density as \(\text{Density} = \frac{\text{Mass}}{\text{Volume}}\).
3. Understand that if mass stays constant and volume increases, density actually decreases because density is inversely proportional to volume.
4. Know the SI unit of density is kilogram per cubic meter, written as \(\mathrm{kg/m^{3}}\), not kilogram per meter.
5. Recognize that two substances with the same mass can have different densities if their volumes differ, since density depends on both mass and volume.