Question

heating curve of substance a which segment represents freezing? e - d d - c c - b b - a temperature (c) 600 500 400 300 200 100 a b c d e f heat added (j)

Explanation:

Step1: Understand phase - change concepts

Freezing is the reverse of melting. On a heating curve, melting occurs when heat is added and the substance changes from solid to liquid. Freezing occurs when heat is removed and the substance changes from liquid to solid.

Step2: Analyze the heating - curve segments

On a heating curve, the horizontal segments represent phase - changes where the temperature remains constant while heat is being added or removed. Segment B - A is the reverse of the melting process (which would be A - B if heating). When going from B to A, heat is being removed and the substance is changing from a liquid to a solid, which is the freezing process. The other horizontal segments D - E represents boiling (going from liquid to gas when heating) and its reverse would be condensation, and C - B represents melting (going from solid to liquid when heating).

Answer:

D. B - A