1) Redox reaction: Al + 3AgNO₃ → Al(NO₃)₃ + 3Ag. oxidation number of aluminium change from 0 to +3 (oxidation). oxidation number of silver changes from +1 to 0 (reduction). 2) Redox reaction: Zn + 2AgNO₃ → Zn(NO₃)₂ + 2Ag. oxidation number of zinc change from 0 to +2 (oxidation). oxidation number of silver changes from +1 to 0 (reduction).