The reactions represented below are all spoontaneous as written. For each, write the anode and cathode half - reactions and indicate the signs of the electrodes.
2 Ag+ (aq) + Pb(s) ----> 2 Ag(s) + Pb2+ (aq)
3 Cu2+(aq) + 2Cr(s) --? 3 Cu(s) + 2 Cr3+ (aq)
Ni2+ (aq) + Zn(s) ? Ni(s) + Zn2+ (aq)