During which process does the temperature of a substance remain constant despite energy transfer?

The correct answer is Melting.

Method lens: First identify the measured quantity, then match the equation or particle idea to the command word. This question asks: During which process does the temperature of a substance remain constant despite energy transfer. The correct response is Melting, because changes of state are explained by particle energy and arrangement. In Changes of state and specific latent heat, the marking point should connect directly to interpret heating and cooling graphs that show temperature changes and flat sections during changes of state. If the question includes values, the working must keep the appropriate unit and operation; if it is an explanation, it must name the relevant particle behaviour or energy change. This item belongs to Internal energy and energy transfers, so avoid answers that switch to a different quantity, confuse heat with temperature, or describe gas pressure without collisions when collisions are the reason. Checkpoint 428 is distinct because it uses this exact question context and the method lens rather than a generic particle-model sentence.