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Reviewed CSCA Chemistry question · Easy

Which process is an example of sublimation?

  1. Solid carbon dioxide (dry ice) turning directly into carbon dioxide gas
  2. Liquid water boiling to form steam
  3. Iodine vapor depositing as solid iodine crystals
  4. Ice melting to form liquid water
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Correct answer

A. Solid carbon dioxide (dry ice) turning directly into carbon dioxide gas

Principle or equation

Sublimation is the direct transition from solid to gas without passing through the liquid phase. Deposition is the reverse (gas to solid).

Why this answer is correct

Dry ice (solid CO2) changes directly to gaseous CO2 at room temperature, which is sublimation. Boiling is liquid to gas (vaporization). Iodine vapor to solid is deposition. Melting is solid to liquid.

Example

Solid iodine heated gently produces purple vapor without melting; this is sublimation.

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