Question

in heating and melting curves, the temperature varies when a substance melts or boils. a true b false

Explanation:

Step1: Recall phase - change concept

During a phase change (melting or boiling), the temperature of a substance remains constant as the heat energy is used for breaking intermolecular forces, not for increasing the kinetic energy (and thus temperature).

Step2: Analyze the statement

The statement says "the temperature varies when a substance melts or boils", which is incorrect.

Answer:

B. FALSE