8 Ag0 + 5 H2SVIO4 4 Ag2ISVIO4 + H2S-II + 4 H2O

This is an oxidation-reduction (redox) reaction:

SVI + 8 e- S-II (reduction)

8 Ag0 - 8 e- 8 AgI (oxidation)

H2SO4 is an oxidizing agent, Ag is a reducing agent.