What is your room?

[Xinfu]

A: What is your room?/Which is your room?/What is your room number?
B: 209.

A and B are talking in the dining hall, who are in college.

Are A's questions all natural and good English?

[poli]

A: What is your room?This is OK too, but not as good/Which is your room?:good:/What is your room number?:good:
B: 209.

A and B are talking in the dining hall, who are in college.

Are A's questions all natural and good English?
Remember that in English contractions are commonly used. It would be more common to hear, what's your room number.

[Nomenclature]

Remember that in English contractions are commonly used. It would be more common to hear, what's your room number.
Especially since they are college students. Older people have a tendency to use contractions less than younger people. In formal writing (i.e. a business letter or academic paper) some people believe contractions are not proper. But in colloquial speech or informal writing, they are very common.

[Xinfu]

Thank you~

[Xinfu]

What is the natural English to ask nationality?

-What is your home country?
-Which is your home country?
-What is your nationality?

[Rusty]

The last question you posted is most natural.
You may also ask, "Where do you come from?"

[Xinfu]

Thank you~