"To whom does the book belong" though older English should also be correct
Who owns the book, whose book is it, and whose is the book, should all be correct. In another exercise it gives the phrase, "cé leis an turtar" with the answer, "whose is the turtle". One would think it should even take, "to whom does the book belong," because that is another way to ask about ownership of an object in English (although it's not written anything like that in Irish, but means the same thing in English).
Does this phrase specifically use 'own?' If so, how would you ask who 'has' the book?
Yes, Cé le is ownership. "Who has the book?" Would be Cé aige a bhfuil an leabhar?
When I click each word it gives me the translation for the whole sentence, is there a reason for this?