Which phenomenon is primarily responsible for heat transfer in liquids and gases?

The phenomenon that is primarily responsible for heat transfer in liquids and gases is convection. Convection occurs when warmer portions of a fluid (liquid or gas) rise while cooler portions sink, creating a circulation pattern. This movement allows for the transfer of heat throughout the fluid.

In a heated fluid, the particles gain energy, move faster, and spread apart, leading to a decrease in density. As a result, the warmer, less dense fluid rises, while cooler, denser fluid moves down to take its place. This continuous cycle of rising and sinking creates a flow that effectively distributes heat across the entire volume of the fluid.

While conduction is another method of heat transfer, it primarily occurs in solids where heat is transferred directly from particle to particle. Friction refers to the resistance encountered by one surface moving over another and does not directly relate to heat transfer in fluids. Insulation describes materials that slow down the transfer of heat but does not itself facilitate heat transfer. Thus, convection is the correct answer as it specifically describes the movement of heat within liquids and gases.