Which two processes are involved when water vapor forms dew and then evaporates?

Which two processes are involved when water vapor forms dew and then evaporates?

• A. Evaporation and melting.
• B. Condensation and evaporation.
• C. Freezing and sublimation.
• D. Deposition and melting.

Answer: (B)

Dew forms when water vapor in the air condenses into liquid water on a cool surface. That liquid can then evaporate back into water vapor when conditions heat up or the surface dries. So the two processes involved are condensation and evaporation. Condensation is gas turning into liquid, and evaporation is liquid turning into gas. The other listed changes involve solid states (freezing, deposition) or a solid–liquid transition (melting) and don’t describe the dew process.

Dew forms when water vapor in the air condenses into liquid water on a cool surface. That liquid can then evaporate back into water vapor when conditions heat up or the surface dries. So the two processes involved are condensation and evaporation. Condensation is gas turning into liquid, and evaporation is liquid turning into gas. The other listed changes involve solid states (freezing, deposition) or a solid–liquid transition (melting) and don’t describe the dew process.