Quote Originally Posted by joeblough10 View Post
We say:

Чья это комната?
Чей это дом?
Чьё это кольцо?
Чьи это коньки?

Why doesn't the demonstrative pronoun "это" agree in gender and number with the nouns it modifies? Why not:

Чья эта комната?
Чей этот дом?
Чьи эти коньки?

Thank you.
"Чей" should agree in number/gender/case anyway.

Actually both groups of questions above are correct, but they have slightly different meanings.

Чья это комната? "Whose room is this?" - here "это"="this" does not really modify noun "room", but refer to some undefined object. "Whose room is this object?"

Чья эта комната? "Whose is this room?" - here "эта"="this" does modify noun "room" and agrees with it.

The first way is more common though.