which of the following compounds conains the Mn3+ ion?

Question

which of the following compounds conains the Mn3+ ion?

A. MnS
B. MnBr2
C. Mn2O3
D. MnO

Answer 1

C Mn2O3

the other compounds contain the Mn2+ ion

Answer 2

The answer is C. The valence of oxide ions is -2, so three of them would have a total charge of -6. To balance that with only two Mn ions, the Mn would HAVE to have a valence of +3.

In A, B, and D, the valence of the Mn is +2. The same logic applies: sulfide has a valence of -2, oxide has a valence of -2, and bromide has a valence of -1. To make a stable salt, the charges MUST cancel.