Of which country is Stockholm the capital? (Word order in questions)

[Don Karnage]

Dear teachers,
It seemed to be an easy question, but different people responded to it in a different way. Consequently, I decided to ask for your help.
Let's define actors:
1) GPT - chat GPT.
2) E.teacher - respectful English teacher in my country.
3) Teenager - Canadian teenager, who speaks English with children all over the world, offering them some spoken practice.
4) Murphy - "English Grammar in use" by Raymond Murphy.

So, here is the variants of question:

1) Of which country is Stockholm the capital?
a) Murphy has this question (thus, it seems to be the best option).
b) E.teacher told, that it's wrong.
c) Teenager said that if you say so, people will understand you, but it is not the best option.
d) GPT said, that it is the most formal/professional option (gramatically correct).

2) Which country is Stockholm the capital of?
a) all actors said the same as #1, but GPT said that #1 is more 'professional' option.

3) Stockholm is the capital of which country?
a) E.teacher said that it is correct option.
b) Teenager said that it is most correct/popular option.
c) GPT said that it is correct and most popular option among native speakers.

4) The capital of which country Stockholm is?
a) GPT said that it's grammatically wrong.
b) E.teacher said that it seems to be correct.

5) The capital of which country is Stockholm?
a) GPT said, that it is correct.
b) E.teacher said that it is wrong.

I'm confused. I kindly ask you to clear the situation.

 

[emsr2d2]

Questions 1, 2, 3 and 5 are grammatically correct. They vary in naturalness. Question 4 is ungrammatical.

 

[Pugliese]

Just to add to emsr2d2's answer. No.3 is the most natural way of phrasing the question

 

[emsr2d2]

Just to add to emsr2d2's answer, No. number/# 3 is the most natural way of phrasing the question.

@Pugliese Please remember that learners will see "English teacher" in your profile and assume that everything you write is correct. On that basis, please make sure that's the case. (Of course, minor typos are always a possibility but omitting punctuation and spacing after punctuation can't usually be blamed on a typo.)
I agree that #3 is probably the most common (from native speakers) but there's nothing unnatural about #1 or #2.

 

[Tarheel]

@Don Karnage Say:

Here are the variants of the question.