"Why is the juice orange?"
Translation:Miksi mehu on oranssia?
Mehu is a mass noun here so the adjective needs the partitive case. You don't use partitive here with countable nouns, for example: "Miksi mehupullo (juice bottle) on oranssi?"
- Mass nouns take the partitive case when they're the object, e.g. "Otan oranssia mehua." ("I take orange juice." as in color, not the fruit.)
- Countable nouns (often) take accusative case instead when they're objects: "Otan oranssin mehupullon." ("I take an/the orange juice bottle.")
But the accusative case is not that simple, it also depends on the verbs used. E.g. katsoa (to look at) VS. nähdä (to see):
- Katson oranssia mehua. VS. Katson oranssia mehupulloa.
- Näen oranssia mehua. VS. Näen oranssin mehupullon.
That sounds more like Finnish Yoda :D It's not wrong but also not a natural sounding word order. That can be found in lyrics or poems, though.
But I think the key is 'oranssia' being an adjective that is defining the subject, and the verb usually always stays next to the subject (it can be before or after it, depending on the type of the sentence, here it can't be before the subject) and that's why it is there between the subject and the adjective.
So "miksi on mehu oranssia" is not possible either?
Would it be reasonable to say that the word order in questions is the same as it would be in the indicative, apart from the question word (either a "mi-" interrogative or a verb suffixed by "-ko") which moves to the front? For example, turning "mehu on tässa" into questions, this could produce "missä mehu on", "onko mehu tässa", "mikä on tässa", "miksi mehu on tässa".
Yes, Finnish doesn't throw the verb before the subject even in questions but sticks to the S-V-O (subject-verb-object) word order even then. This is why I often do the mistake in English of not including do/does before the subject, e.g. instead of writing "Why does he do that?" I sometimes accidentally write "Why he does that?" or so.
All your examples sound fine what comes to the word order, that is how it's mostly done. However, pay attention to the vowel harmony as it's "tässä" and not "tässa" - front vowels (ä, ö, y) can't be in the same words with back vowels (a, o, u) unless it's a compound word (two separate words written as one, e.g. 'isoäiti') or a loanword (e.g. 'olympialaiset').
It's the safest to use this word order even with some interrogation words it's also possible to have the verb before the subject. "Miksi on mehu oranssia?" sounds wrong (probably because of the adjective defining the 'mehu'!) but e.g. with "missä" you can have the verb before or after the subject and it's fine both ways. It's still more natural to say "Missä mehu on?" but "Missä on mehu?" is not wrong either. I think this just puts the emphasiz on the verb so they're asking where IS it, instead of asking where is the JUICE. Or something, the more I think about it, the less I understand (and I'm a Finn). We usually emphasize words with the tone because the word order doesn't do that too well.
I think the distinction between topic and comment may be relevant here. (A topic is the context known to the listener while a comment is the new information provided by the speaker.) Many European languages with so called "free" word order actually use it to mark this distinction, quite usually by moving topic to the front and comment to the end of the sentence. My native Czech does that (together with other Slavic languages) and I have expected the same from Finnish. So my current working hypothesis for affirmatives is that (1) "tässä on mehu" is said when the discussion is about things that are here and the juice is just being introduced to the discourse ("there is a juice here"), while (2) "mehu on tässä" would be used when already talking about the juice and its position is the new information ("the juice is here"). Are my expectations correct?
Anyway, questions are a bit more tricky and my native word order habits do not work in Finnish apparently (they gave me "miksi on mehu oranssia").