Improper translations: "Whose is the coat" or "whose is the shirt" as a translation of "À qui" (being a part of a sentence). Generally I believe you cannot end a sentence in a preposition. Therefore, the translation should read, "Whose coat is it?" or "Whose shirt is it" or rather "To whom does that shirt belong?"
Technically, you are correct, but having a preposition at the end of a sentence has been acceptable in modern English for some time now.