Which term describes heat transfer from one place to another by the flow of molecules from one place to another?

• A. Conduction
• B. Radiation
• C. Convection
• D. Evaporation

Answer: (C)

Heat moving by the bulk flow of a fluid—like air or water carrying energy as it circulates—is convection. In convection, the fluid itself moves, so heat is transported with that moving mass (hot portions rise as they’re less dense and cooler portions sink). This is different from conduction, where heat transfers through direct contact between molecules without any overall fluid movement, and from radiation, which transfers energy through waves without needing a medium. Evaporation is a phase change, not a mechanism of moving heat via the flow of molecules. So convection best fits the description.