What is the charge on each of the following complex ions?
A. hexaaquachromium(II), [Cr(H2O)6]^?
B. tris (carbonato)cobaltate(III), [Co(CO3)3]^?
C. amminepentabromoplatinate(IV), [Pt(NH3)Br5]^?
Express the charges numerically, in the order that the complexes are listed, separated by commas. For nonzero charge, be sure to include the sign (e.g., +1, -2, +3).