(Where's/Where are) the guitar?
Where is the guitar? - It's on the bed
(Where's/Where are) the birds?
Where are the birds? - They are on the sandcastle
Where's the photo?
Where's the photo? - It's in the book
(Where's/Where are) the book?
Where is the book? - It's on the desk
(Where's/Where are) the shells?
Where are the shells? - They are in the box
Where's the pencil?
Where's the pencil? - It's on the desk.