Using this table
Fe (s) + CuSO4(aq) --> FeSO4 (aq) + Cu(s)
0 +2+6-2 +2+6-2 0 (oxidation numbers)
0 +2+6-8 +2+6-8 0 (total contribution to charge)
What would the answer be for the following?
Pb + CuSO4 --> Cu + PbSO4
(oxidation numbers)
(total contribution to charge)
Zn + CuSO4 --> Cu + PbSO4
(oxidation numbers)
(total contribution to charge)
Zn + Pb(NO3)2 --> Pb + Zn(NO3)2
(oxidation numbers)
(total contribution to charge)