Two electrons are transferred in this reaction.

Ag+ + I- ? AgI
HC2H3O2 + OH- ? C2H3O2 - + H2O
NaCl (l) ? Na (l) + Cl2 (g)
Mg + O2 ? MgO
Fe2+ + 8H+ + MnO4- ? Fe3+ + Mn2+ + 4H2O