Uter, utra, utrum

Hi,
I have a question about the grammatical construction of “uter, utra, utrum” when it is an interrogative.
What is the case of the noun that follows “uter, utra, utrum”?
I saw sometimes that it was followed by a genitive, other times by “ex” + ablative, and also in the same case as “uter, utra, utrum”:

In utrā casā est lūlia? (ablative as utra)
Utram amphoram bibēs? (accusative as utram)
Utrum scelerum iste fēcit? (genitive)
uter ex his ? (ex + abltative)

Which one is correct? If all are correct, then when do we use each construction?
Thank you,
Anto

You can think of it as the equivalent of English “which?”, when there’s just two that are in question.

But first a clarification: In “Utrum scelerum iste fēcit?” (your third sentence) utrum is not genitive but neuter accusative, the object of fecit, “Which of the crimes did he commit?” (i.e. which one of the two)

The others:
In which house is Julia? (There are two houses. Which one is Julia in?)
Which winejar will you drink?
Which from these? i.e. Which one out of these two? (uter nom.masc., the subject.)

From here on your best bet is probably just to observe how it’s used, unless you have follow-up questions.

Regarding your clarification on the genitive, you are right; but I intended that “scelerum” is in the genitive (not utrum).
However, it is still not very clear for me, because I would have said:

In utrā casārum est lūlia?
Instead of: In utrā casā est lūlia?

And: Utram amphorārum bibēs?
Instead of: Utram amphoram bibēs?

And: Uter ex hōrum?
Instead of: Uter ex his ?

Or maybe both versions are correct? Then, why not say also: Utrum scelus iste fēcit?

Just as in English you can say “Which house?” and “Which of the houses?”, so in Latin you could say “utra casa?” and “utra casarum?” It’s largely a matter of local context. The partitive genitive (as in “uter horum?”) is common in Latin, and is often used with words meaning which, each, neither, all, etc. etc. You should let usage be your guide.

Thank you, now it is clear.