Question

It is generally seen that, when a substance absorbs heat energy, its heating curve shows two plateaus. Which phenomenon is indicated by these plateaus?
Responses
A meltingmelting
B boilingboiling
C phase changephase change
D crystallization

Answer 1

The plateaus in a heating curve indicate a **phase change** where the temperature remains constant while the substance transitions from one state to another. The first plateau corresponds to melting (solid to liquid) and the second plateau corresponds to boiling (liquid to gas). Therefore, the most comprehensive answer is:

**C phase change**