"क्या वहाँ कोई है?"

Translation: Is someone there?

[avi448025]

"Is there anybody?" ..is it not also a right sentence..?,,

[vinay92]

In your sentence, 'there' is used as a pronoun which roughly means 'there exists'. We want to use the noun 'there' (corresponding to वहाँ) which means 'that place'.

So, switching around the words, "Is anybody there" seems like a good enough translation and should be accepted.

Hindi does not differentiate much between 'someone' and 'anyone'. You can use "कोई" and "कोई भी" respectively for the two but in sentences like the one we have, both 'someone' and 'anyone' work.

[Renu639382]

I think "Is there someone there" is more correct

[Wilbur111]

Can this be "is anyone there?"?

[vinay92]

Yes, it can.

[kooprad]

Is this what we should say when someone knocks on the door?

[vinay92]

You can but it is more common to drop the वहाँ.
क्या कोई है? (Is anyone there?) or कौन है? (Who is there?).
The वहाँ in this sentence is 'there' meaning 'at that place' rather than just talking about the existence of something.

[IvanIven]

Is there any difference between कोई और किसी???

[IvanIven]

Which would be the cases for each?

[vinay92]

किसी is the oblique form of कोई and is used when it is the object of a postposition.
For example, in 'क्या मैं किसी से पूछ सकता हो? (Can I ask someone), किसी is used instead of कोई because it is the object of से.