Which of the following are the three modes of heat transfer?

The three primary modes of heat transfer are conduction, convection, and radiation.

Conduction is the transfer of heat through a solid material, occurring when there is direct contact between particles. In this process, energy is transferred from the hotter region of the material to the cooler region via collisions of particles.

Convection involves the transfer of heat through fluids (liquids and gases) caused by the movement of the fluid itself. When a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks, creating a circulation pattern that effectively transfers heat throughout the fluid.

Radiation is the transfer of energy through electromagnetic waves. This process does not require a medium; therefore heat can be transferred through a vacuum, such as how sunlight reaches Earth.

Each of these methods demonstrates a unique mechanism for transferring thermal energy, making them fundamental concepts in thermodynamics. The other choices mention processes like evaporation or condensation, which are not modes of heat transfer but instead describe phase changes of substances or specific heat exchange processes.