Matching phase changes to diagram labels

Steps:

• Label W shows liquid heating to gas: boiling (liquid to gas).
• Label X shows gas cooling to liquid: condensation (gas to liquid).
• Label Y shows liquid cooling to solid: freezing (liquid to solid).
• Label Z shows solid heating to liquid: melting (solid to liquid).

Why D is correct:

• D sequences boiling, condensation, freezing, melting, aligning with definitions of endothermic (boiling, melting) and exothermic (condensation, freezing) phase transitions.

Why the others are wrong:

• A: Starts with condensation (gas to liquid), mismatches W's liquid-to-gas process.
• B: Places melting before freezing, reverses Y and Z solid-liquid changes.
• C: Begins with boiling but swaps melting and freezing, inverting Y and Z.

Final answer: D