Mass remains constant upon heating

Steps:

• Heating increases the kinetic energy of copper atoms, causing thermal expansion.
• Mass is the total amount of matter, which stays fixed without adding or removing material.
• Volume expands due to increased atomic vibrations, reducing density.
• Temperature rises as heat is added, by definition.

Why B is correct:

• Mass is conserved in closed systems, per the law of conservation of mass; heating doesn't create or destroy atoms.

Why the others are wrong:

• A: Density decreases as volume increases while mass stays constant (density = mass/volume).
• C: Temperature increases directly from heat input.
• D: Volume expands due to thermal expansion coefficient of copper.

Final answer: B