What is the state called when heat flows from a hotter region to a cooler region until temperatures are equal?

• A. Thermal Equilibrium
• B. Calorimetry
• C. Specific Heat
• D. Endothermic

Answer: (A)

Thermal equilibrium is the state where heat flow between regions stops because their temperatures have become equal. When heat moves from a hotter region to a cooler one, the transfer continues until a common temperature is reached, at which point there is no driving force for further heat exchange. That final, balanced condition is thermal equilibrium. In real problems, the exact common temperature depends on the masses and specific heats of the bodies involved, but the defining idea is that no net heat transfer remains once the temperatures match. Calorimetry is the measurement of heat transferred during such processes, specific heat is a property that tells how much heat is needed to raise the temperature of a substance, and endothermic describes heat absorption during a process—not the resulting equal temperatures themselves.