K2Cr2VIO7 + 2 NIIO + 4 H2SO4 2 HNVO3 + Cr2III(SO4)3 + K2SO4 + 3 H2O

This is an oxidation-reduction (redox) reaction:

2 NII - 6 e- 2 NV (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

NO is a reducing agent, K2Cr2O7 is an oxidizing agent.