RSTP(Rapid Spanning Tree) is configured on a bridge. All ports of this bridge are "trunk" ports and are part of vlan “x”. Will the BPDUs sent out of this bridge be tagged?
No. RSTP BPDUs are never tagged irrespective of the port type(access/trunk). Because RSTP BPDUs on being received by a bridge are sent to the CPU for processing if the bridge understands RSTP or are discarded. So, they need not be forwarded.