Which ion indicates the perbromate compound?

The perbromate ion is represented by the formula BrO4(-). This ion is an example of a polyatomic ion where bromine (Br) is bonded to four oxygen atoms and carries an overall negative one charge.

In nomenclature of oxyanions, the prefix "per-" signifies that the ion contains the highest number of oxygen atoms for a given oxidation state of bromine. Thus, perbromate indicates the ion with the most oxygens, which in this case is four.

The other ions mentioned do not represent perbromate. For instance, BrO(-) represents hypobromite, BrO2(-) signifies bromite, and BrO3(-) indicates bromate. Each of these ions has fewer oxygen atoms than perbromate and corresponds to different oxidation states of bromine, which is why they do not qualify as perbromate.