Jawabanmu

2014-06-04T07:45:12+07:00
BaO
+2 -2
SO42-
+6 -2
H2C2O4
+1 +2 -2
Fe2O3
+3 -2
BaO
O biloksnya -2, jadi Ba biloksnya +2
SO42-
ok
S=O4-2
S=+8-2
S=+6