16 NaSO 17- Find the Charges(Oxidation number) of the underlined elements: A) Mgso Mg- S- PD C) Fe(COs)s Fe- o- Solution A) MgSO4 Mg oxidation number = +2 S = +6 ( SO4 has -2 charge , S ( OS) + 4O ( OS) = -2 , S (OS) + 4( -2) = 0 , S (OS) = +6) O = - 2 B) Pb3 (PO4)4 , PO4 has -3 charge , 3 Pb (OS) + 4 ( -3) = 0 , Pb (OS) = 4 Pb = +4 P = +5 O = -2 C) Fe2(CO3)3 , 2 Fe (OS) + 3 CO3 ( OS) = 0 , 2Fe (OS) + 3 ( -2) = 0 , Fe (OS) = +3 Fe = +3 C = +4 O = -2 .