Concept:A saturated vapour is a vapour that exists in dynamic equilibrium with its own liquid.
Explanation:In a closed container, liquid molecules constantly escape into the vapour phase.
At the same time, vapour molecules constantly return to the liquid phase.
When the rate of evaporation equals the rate of condensation, the vapour is saturated.
This condition is described as a dynamic equilibrium because molecules are still moving between phases, but there is no net change.
If more molecules return to the liquid than leave it, the vapour is not saturated; it is condensing.
Saturation does not require a fixed temperature or atmospheric pressure.
Therefore, the correct description is that a dynamic equilibrium exists between liquid molecules and vapour molecules.
Answer:A. a dynamic equilibrium exists between liquid molecules and the vapour molecules.