Question

a substance is placed in a closed vessel. the substance is continuously heated and its temperature is monitored, leading to the heating curve below. five regions of the heating curve are labeled with a number.
chart: temperature (y - axis) vs time of heating (x - axis), with regions 1, 2, 3, 4, 5 labeled
during which numbered region(s) of the graph does the addition of heat lead to a temperature change? select all that apply.
tap to select or deselect an answer. select all that apply.
1 2 3 4 5

Explanation:

In a heating curve, regions with a positive slope (where temperature increases with heat addition) are when heat leads to temperature change. Flat regions (like 2 and 4) are phase changes (melting, boiling) where heat energy is used for phase transition, not temperature change. Regions 1, 3, 5 have upward slopes, so heat added increases temperature.

Answer:

1, 3, 5