Note: I'm not exactly an expert in this, so it's possible I've made some mistakes. I'm sure someone in the comments will correct me if that's the case.
#1: As the other answer says, this is the antenna for one of the two-way VHF radios. It's on the bottom because airplanes are typically above the ATC facility they're talking to, and so putting the antenna on the bottom may give it a better line of sight.
#2: This is the antenna for the marker beacons, part of ILS.
#3: This is the UHF antenna, used for both the transponder and DME (if installed).
#4: This is one of two navigation antennas (the other one is on the other side of the tail, not visible in this photo). They're mounted at a 45 degree angle to the aircraft centerline, and are typically used to navigate via VORs. They may also feed other navigational equipment.
#5: I'm not sure about this one. I think it might be the ELT antenna.
#6: This is the antenna for the other two-way VHF radio. It's mounted on top on the theory that, if you can't get a good signal on one radio, another radio with an antenna in a different position might give you better reception.
#7, #8, and #9: These are all satellite receivers for stuff like GPS and satellite weather, though you can't tell from the outside which is which.