Complete and balance the following equation:

Mn²⁺ + PbO₂ $$\to$$ $$MnO_4^-$$ + H₂O

Complete and balance the following equation:

$$ClO_3^-$$ + I^- + H₂SO₄ $$\to$$ Cl^- + $$HSO_4^-$$

Complete and balance the following equation:

S + OH^- $$\to$$ S^2- + $$S_2O_3^-$$

Complete and balance the following equation:

Ag⁺ + AsH₃ $$\to$$ H₃AsO₃ + H⁺