No, the rule: [he/she/it + is + modified noun = c'est un/une + noun] is also valid in the interrogative and negative modes:

• it is our room = c'est notre chambre

• is it our room? = est-ce notre chambre ?

• it is not room = ce n'est pas notre chambre

• is it not our room? = n'est-ce pas notre chambre ?

"room" is in singular, so "notre chambre"

"our roomS" = nos chambreS

You may have noticed how Duo can be binary. So, every translation should be back-translatable to the original sentence, in meaning of course, but also in style, register of speech, etc.

"the room, is it ours?" is what you get when you back translate your version, and it is another (more emphatic) way of asking the question.

However, in real life, what you suggest works, although it would be better with "cette" instead of "la". There is a kind of incompatibility between something specific and unique "la chambre" and a possessive pronoun. With "la chambre", you can identify it as "elle est à nous".

@StarryThresh your sentence souds a bit weird in french (I am a french native). You can say "Cette chambre, est-ce la notre ?" It will better

Here are the 3 alternative constructions for this question:

• formal: est-ce notre chambre ? (Verb-Subject inversion)
• standard: est-ce que c'est notre chambre (est-ce que = is it that)
• informal/in speech: c'est notre chambre ?

You missed the verb in "est-ce que [...] notre chambre ?"

If you parse it out:

• formal: est-ce notre chambre ? = is it our room?
• standard: [est-ce que] c'est notre chambre ? = lit. [is it that] it is our room?
• informal: c'est notre chambre ? = it is our room?