"Is this your apple?"
Translation:Это ваше яблоко?
This is inconsistent. There is another lesson in this section which asks for the translation of "Is this your water?" The answer «Эта твоя вода?» is not accepted. The only word order accepted is «Эта вода ваша/твоя?» So, which one is it? I asked my wife, who is a native Russian speaker from Russia and she said that for her, it's the same - fully cognizant of the fact that she natively acquired the language and can't list all the formalities and rules. That said, her explanation to me was that the rising intonation makes it a question, and while the emphasis of the question is different in each case, they both ask the same question at the end of the day - "Is this your apple?" / "Is this apple yours?" At the very least, if something is going to be unacceptable in one question of the same sort, it should be unacceptable in all others of the same sort. Either that or both word orders should be accepted in all questions of the same sort.
I think it would have to be either это твоя вода Or эта вода твоя Difference between это "this is" (demonstrative pronoun) and этот/эта/это/эти "this" (demonstrative adjective). Эта твоя вода? is not correct. In this exercise, on the other hand, the demonstrative pronoun это happens to be the same as the demonstrative adjective это simply because яблоко is neuter, so I suppose either word order would work even without changing это.
Ваш is your/yours, used with a masculine singular noun. Example: ваш стол (your table).
Ваша is your/yours, used with a feminine singular noun. Example: ваша лошадь (your female horse).
Ваше is your/yours, used with a neuter singular noun. Example: ваше яблоко (your apple).
Ваши is your/yours, used with plural nouns regardless of gender. Example: ваши столы, ваши лошади, ваши яблоки, ваши тарелки и ложки, etc.)
Note that Ваш/ваша/ваше/ваши is used when talking about either (1) you as a plural (as in, speaking to Mom and Dad) or (2) you in the singular, but I may not know you that well or I want to indicate respect (as in, speaking to my boss Ivan Ivanovich or to my grandmother who is a little scary and deserving of respect).
Note also that you can say, "Ваши тарелки и ложки" because I'm talking about plural objects (and thus don't have to differentiate by gender), but if I'm talking about two nouns of different genders, I should make the words agree: "ваша мама и ваше такси." (Мама being feminine, and такси being neuter.)
(Edited for clarity in first paragraph)