"Who is that boy's mother?"

[Soolrak]

Isn't toho used for the Accusative case? If I am correct, why is this word here? According to me, it should have been to, since it's the Nominative case (and chlapce the Genitive, yes).

I am sure I am wrong, but please explain to me why, I need to know. Thank you in advance! =)

[VladaFu]

nom. ten

gen. toho <---

dat. tomu

acc. toho

loc. tom

instr. tím

It is genitive. The subject matka is irrelevant here.

[Soolrak]

Oh, I see. Sorry for the mistake and thank you very much for all your help. I really appreciate it!

[Randonneur3]

If translating 'who is the mother of that boy?' (no possesive apostrophe) would it be the same?

[VladaFu]

of course, it is accepted

[Giovanni919769]

May I also say "kdo je toho chlapce matka" or would it be incorrect?

[VladaFu]

No, that is very unusual even though you may encounter it in the 19th century poetry. "toho chlapce" acts like a non-agreeing modifier (does not change with cases) and should be placed after the noun.