Name the compound re2o5. use a roman numeral after the name of the cation

Answer is: name of the compound Re₂O₅ is rhenium (V) oxide.

In this chemical compound atom of rhenium has oxidation number + 5 and atom oxygen has oxidation number - 2, chemical compound rhenium (V) - oxide has neutral charge (2· (+5) + 5· (-2) = 0).

Roman five is for valence of rhenium in this compound.