Which statement about conduction is true?

• A. It transfers heat via particle interactions with no net mass transfer
• B. It requires a medium with fluid flow
• C. It occurs only at high temperatures
• D. It relies on phase changes

Answer: (A)

Conduction is heat transfer through microscopic interactions within a material, with no net movement of mass. Energy moves from regions of higher temperature to lower temperature by particle interactions and, in metals, by free electrons and lattice vibrations, but the material as a whole doesn’t flow or bulk-move. That’s why the statement is true: heat can travel through a solid or fluid simply because particles collide and vibrate, transferring energy along the gradient without any overall mass transfer.

This differs from convection, which relies on bulk fluid motion to carry heat, and from heat transfer due to phase changes like melting or vaporization, which involve latent heat. Conduction also does not require high temperatures; it occurs whenever there is a temperature difference, with the rate governed by the material’s ability to conduct heat.