(from Elementary Lessons in Physical Geography by Sir Archibald Geikie, 1912) 17. By the term Water-vapour, or Aqueous vapour, is meant the invisible steam always present in the air. Every one is familiar with the fact, that when water is heated it passes into an invisible vapour or gas, which becomes dissolved in the air. A vessel of water, for instance, may be placed on a table in the middle of a room, heated by means of a spirit lamp till it boils, and kept boiling till the water is entirely driven off into vapour or evaporated. The air in the room shows no visible change, though it has had all this water-vapour added to it.

Which of the following most belongs in a set of notes about the passage?

Water vapor was added into the air.
Everyone knows that water evaporates.
No one can see any evaporated water.
“Aqueous vapor” is evaporated water.