"Чьё это яблоко?"
Translation:Whose apple is it?
Could this also mean "Whose is this apple?" (For example, a teacher finds a particular apple in the classroom and wonders whose it is.) Duolingo did not accept that answer.
It certainly can. You should've reported it.
These examples might be helpful:
Чья это книга? = Whose book is this?
Чья эта книга? = Whose is this book?
I can understand the meaning of the sentence "whose is this apple?" easily but it just doesnt sound right to my ears.
They mean the same thing, don't they? But the natural word order in English is whose apple, not whose is.
It depends on the gender and number of the object,
чей - masculine
чья - feminine
чьё - neutral
чьи - plural
I do not quite understand how the interrogative pronouns meaning 'Whose?' (e.g. Чей, чья) can have separate nominative and genitive forms, since ''whose' is in itself possessive (i.e. genitive) in meaning. Do the genitive forms only come into play after certain prepositions which normally take that case?