Here's why:
* Conservation of Mass: The law of conservation of mass states that matter cannot be created or destroyed, only transformed.
* Phase Change: Condensation is a phase change where water vapor (gas) changes into liquid water. The molecules themselves don't disappear or get added.
* Density Change: While the volume of the water changes drastically (gas takes up much more space than liquid), the total number of water molecules remains constant.
Therefore, the total mass of the water sample remains the same, even though its state changes.
