[CO(NH3)5Br]SO4 and [CO(NH3)5SO4]Br are ionisation isomers.
Aqueous solution of [CO(NH3)5Br]SO4 will give a white ppt whit BaCl2 solution. The ppt with BaCl2 solution. The ppt is insoluble in conc. HNO3 confirming presence of free SO2−4 ion. Aqueous solution of [CO(NH3)5SO4]Br will not give this test.
[CO(NH3)5Br]SO4⇌[CO(NH3)5Br]2++SO2−4
BaCl2+SO2−4→BaSO4↓white ppt+2Cl−
[CO(NH3)5SO4]Br⇌[CO(NH3)5SO4]++Br−
BaCl2+Br−→No ppt