\(\begin{align} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,O\overset{-1}{\mathop{Cl}}\, \\ Ca\,< \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overset{+1}{\mathop{Cl}}\, \\ \end{align}\)
$MnO_4^ - \,\, + \,\,{C_2}O_4^{2 - }\,\, + \,\,{H^ + }\, \rightarrow \,\,M{n^{2 + }}\, + \,C{O_2} + \,{H_2}O$