Use the graph above to answer this question. A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as sho...

Use the graph above to answer this question.

A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as shown in OPQR. The section PQ indicates that X is

Answer Details

Based on the graph, section PQ represents a solidification process, where the sample X is cooling and changing from a liquid state to a solid state. Since the cooling curve shows a sharp decrease in temperature without any plateau, it indicates that the solidification process is happening at a constant temperature. This suggests that X is a pure compound with a fixed melting and freezing point. Therefore, the correct answer is: "a pure compound."