10 Cr0 + 6 HNVO3 3 N20 + 5 Cr2IIIO3 + 3 H2O

This is an oxidation-reduction (redox) reaction:

6 NV + 30 e- 6 N0 (reduction)

10 Cr0 - 30 e- 10 CrIII (oxidation)

HNO3 is an oxidizing agent, Cr is a reducing agent.