How many connections could node's mongoose and mongodb itself handle? Will the server crash?

Okey, so i was having a thought about building some kind of API built on NodeJS with mongoose. I read that mongoose uses 1 connection per app.

But let us say that we have 300 000 users joining a room too answer some questions ( real-time ), will mongoose/mongodb handle it? Or will the server itself even handle it?

via Robin Ryden