on/in

English as a Second Language English Vocabulary, Grammar and Idioms
1
  1. What floor is your office on?
  2. What floor is your office in?
    Please correct the above.
    Thanks.
2

1 is correct.

3

Beeesneees,

  1. We are living in/on the ground floor. (BE)
  2. We are living in/on the first floor. (AE)
    Please correct the above.
    Thanks.
4

Both should be ‘on’.
Ground floor and first floor are different floors, it is not a case of BrE/AmE.