Question

considering the temperature vs. time graph below, how does the temperature at the beginning of a change of state compare with the temperature at the end of the change?
the temperature is always lower.
the temperature is always the same.
the temperature is usually lower.
the temperature is usually higher.

Explanation:

Step1: Analyze the temperature - time graph

In a temperature - time graph for a change of state, during the change of state (e.g., freezing or melting), the temperature remains constant. But when comparing the temperature at the beginning and the end of the overall change (not just the phase - change part), we look at the starting and ending points of the entire process.
The starting temperature (left - most point) is higher than the ending temperature (right - most point) in the given graph.

Answer:

The temperature is usually lower.