4 Zn0 + HClVIIO4 + 4 H2SO4 4 ZnIISO4 + HCl-I + 4 H2O

This is an oxidation-reduction (redox) reaction:

4 Zn0 - 8 e- 4 ZnII (oxidation)

ClVII + 8 e- Cl-I (reduction)

Change the oxidation states