2) No, it isn't. It's under the desk.
3) No, they're not. They're next to the pencil case.
4) No, they're not. The're under the chair.
5) No, it isn't. It's on the chair.
6) No, they're not. They're in the bag.
b)
2) the rubber is in the pencil case.
3) the sandwiches are under the desk.
4) the camera is on the desk.
5) the chair is next to the desk.