Which of the following best describes how increasing temperature generally affects the density of a material?

• A. Density remains unchanged regardless of temperature.
• B. Density increases because mass increases with temperature.
• C. Density decreases because most materials expand when heated.
• D. Density increases because most materials contract when heated.

Answer: (C)

Verified step by step guidance

1. Recall the definition of density, which is given by the formula \(\text{Density} = \frac{\text{Mass}}{\text{Volume}}\).
2. Understand that when temperature increases, the mass of a material generally remains constant because heating does not add or remove matter.
3. Recognize that most materials expand when heated, meaning their volume increases as temperature rises.
4. Since mass stays the same and volume increases, the density, which is mass divided by volume, will decrease.
5. Therefore, increasing temperature generally causes the density of a material to decrease because of thermal expansion.