In the xenon written-response scenario for Pure substances, explain how pure substance chromatography supports this objective: Explain that a pure element or compound melts and boils at specific temperatures..

A high-scoring answer should explain explain that a pure element or compound melts and boils at specific temperatures. Use evidence before identification: name the relevant test or measurement, state the observation, and then connect the result to Pure substances.

The important distinction is that pure substance must be identified from single element or compound / fixed melting point; answers that swap in a different test or result do not match Pure substances. A complete answer should use the approved objective wording, include the relevant evidence, and avoid unsupported identification claims.