6) He has an access ..... all rooms of the hotel.
Explanation: 'access to' means to have permission or authority
7) The plan fell ...... because of their laziness.
Explanation: "fell through" means to collapse or didn't work
8) She lives ...... a one bedroom flat ...... the second floor.
Explanation: 'in' indicates position, e.g. inside something and 'on' is used for the number of the floor.
9) Yesterday, I saw apples .... the tree.
Explanation: 'on' can mean attached to.
10) His house is ......... the way from Delhi to Chandigarh.
Explanation: We use 'on' to show position on a line such as a road, river, etc.