Which of the following is an example of sublimation?

• A. Ice melting to form liquid water
• B. Liquid ethanol evaporating to form ethanol vapor
• C. Water vapor condensing to form liquid water
• D. Solid CO2 (dry ice) changing directly into CO2 gas

Answer: (D)

Verified step by step guidance

1. Understand the definition of sublimation: it is the phase transition where a substance changes directly from a solid to a gas without passing through the liquid phase.
2. Analyze each option to determine if the phase change involves skipping the liquid phase:
3. - Ice melting to form liquid water involves solid to liquid, so it is melting, not sublimation.
4. - Liquid ethanol evaporating to form ethanol vapor involves liquid to gas, so it is evaporation, not sublimation.
5. - Water vapor condensing to form liquid water involves gas to liquid, which is condensation, not sublimation.
6. - Solid CO2 (dry ice) changing directly into CO2 gas involves solid to gas without becoming liquid, which matches the definition of sublimation.