One of the "correct" answers does not make sense in English: "There is a flight of staircase"
Well that would be spectacular, a flight of staircases! In a chevron formation, no doubt.
The more common English idiomatic usage would be "a flight of stairs". Edited because I misread the original.
is there a different word in french for stair and staircase? Because I put "there is a stair" and it was not accepted.
I think of a stairwell as an enclosed area. It is still a flight of stairs but it is set off by fire doors. I don't know if there is a separate word for that in French.
Just out of curiosity, since I got it wrong, how would be "ladder" in French?
What about "there is an escalator"? In English, you'd make a distinction between stairs and escalators.