Question

In most materials, as heat energy is absorbed, density increases or decreases?

Answer 1

In most materials, as heat energy is absorbed, the density decreases.

Answer 2

In most materials, as heat energy is absorbed, the density decreases.
IF a certain object is heated, it might appear bigger than usual because it expands as the molecules inside moves faster than usual. However the mass of it stays the same while the density decreases.