4 CuO + 2 NH4Cl → 4 H2O + 3 Cu + N2 + CuCl2
This is an acid-base reaction (neutralization): CuO is a base, NH4Cl is an acid.
This is an oxidation-reduction (redox) reaction:
3 CuII + 6 e- → 3 Cu0 (reduction)
2 N-III - 6 e- → 2 N0 (oxidation)
CuO is an oxidizing agent, NH4Cl is a reducing agent.