2 N-IIIH4Cl + K2Cr2VIO7 N20 + Cr2IIIO3 + 2 KOH + 2 HCl + 2 H2O

This is an oxidation-reduction (redox) reaction:

2 N-III - 6 e- 2 N0 (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

NH4Cl is a reducing agent, K2Cr2O7 is an oxidizing agent.