I know that the mandatory liaisons for prepositions are the following:
Dans = In [dɑ̃]
En = In [ɑ̃]
Sans = Without [sɑ̃]
Chez = At (“z” sounds like “z”) [ ʃe] VERIFIED
Sous = Under… [su]
Dès = From [de̞]
But how about Sur = On?
As in "Sur un" is [syr œ̃] OR [sy‿rœ̃] ???