Since this is a BBQ forum, I would say none of them are smoke stacks.3 grouped together, 1 off by itself... 3 together have 1 black, 2 grey pipes. Solo is grey...
black is probably gas and the grey look like electrical conduit
Not much info but if they have some type of cord in them, those are electrician stubb outs. They go back to your circuit breaker box. They are for pulling wire later on a unfinished space.