10 CrIIO + 2 HNVO3 N20 + 5 Cr2IIIO3 + H2O

This is an oxidation-reduction (redox) reaction:

2 NV + 10 e- 2 N0 (reduction)

10 CrII - 10 e- 10 CrIII (oxidation)

Change the oxidation states