H₂Se^IVO₃ + 2 Zn⁰ + 4 HCl → 2 Zn^IICl₂ + Se⁰ + 3 H₂O

This is an oxidation-reduction (redox) reaction:

Se^IV + 4 e^- → Se⁰ (reduction)

2 Zn⁰ - 4 e^- → 2 Zn^II (oxidation)

H₂SeO₃ is an oxidizing agent, Zn is a reducing agent.