The correct answers are Your keys are on the kitchen table. and I saw your jacket on the second floor.

We use on to talk about surfaces (like a table, a sofa, or a ceiling) and for the floors of a building.

"In the ceiling" is incorrect because the ceiling is a surface, so it should be on the ceiling.

"At the sofa" is incorrect because a sofa is a surface we place things on, so it should be on the sofa.