Chemistry

Problem

Balance the following half-equations: a.

\text{SO}_2 \rightarrow \text{SO}_4^{2-}

\text{MnO}_4^- \rightarrow \text{Mn}^{2+}

\text{BrO}_3^- \rightarrow \text{Br}_2

\text{Cr}^{3+} \rightarrow \text{Cr}_2\text{O}_7^{2-}