Home › BECE (Ghana) › Science › Changes of State › Drops of water appear on the outside of a cold g…
Drops of water appear on the outside of a cold glass. What has the water vapour in the air done?
AIt has warmed and turned into a liquid
BIt has cooled and turned into a liquid
CIt has cooled and turned into a solid
DIt has warmed and turned into a gas
Answer & Solution
Correct answer: B. It has cooled and turned into a liquid
1. The air around the glass carries invisible water vapour.
2. The cold glass takes energy away from the vapour particles touching it.
3. With less energy those particles slow down.
4. Slower particles feel the forces of attraction between them and pull together.
5. They join into tiny droplets of liquid water, and this change is condensation.
6. Warming would do the opposite and keep the water as vapour.
7. Turning into a solid would need cooling much further, all the way to freezing.
_Source: Siyavula Natural Sciences Grade 8 (CC BY 4.0), Condensation and solidifying_
Related questions