Oxidation State numbers

Question

For Fe3+ i got 3+ b/c Oxidation state monatomic ion = ionic charge and i got that answer wrong. i am receiving wrong answers for these below aswell.
I used these rules for the following

-Alkali metals are always +1; alkaline earths are always +2.

-Sum of oxidation states is zero for neutral compounds, and equal to the overall charge for polyatomic ionic species

CuCl2= Oxidation states of Cu? Cl2?
CO_2 Cu? O?
MnO_4^2- Mn? O
HSO_4^- H? So

Answer 1

+3 is correct for Fe^+3.
Cu in CuCl2 is +2.
Cl in CuCl2 is -1 each.
C in CO2 is +4; O is -2 each.
Mn in MnO4^- is +7; O is -2 each
H in HSO4^- is +1; SO4^-2 is -2; S is +6 and O is -2 each.