Reduction half reaction-
\(Cl_2 \rightarrow Cl^-\)
Balancing chlorine atom-
\(Cl_2 \rightarrow 2Cl^-\)
Balancing charges-
\(Cl_2 + 2e^-\rightarrow 2Cl^-\) ....(i)
Oxidation half reaction-
\(Cl_2 \rightarrow Cl{O_3}^-\)
Balancing Cl atom-
\(Cl_2 \rightarrow 2Cl{O_3}^-\)
Balancing O atom-
\(Cl_2 + 6OH^- \rightarrow 2Cl{O_3}^-\)
Balancing H atom-
\(Cl_2 + 12OH^- \rightarrow 2Cl{O_3}^- + 6H_2O\)
Balancing charges-
\(Cl_2 + 12OH^- \rightarrow 2Cl{O_3}^- + 6H_2O+ 10e^-\) ....(ii)
Adding equation (i) after multiply by 5, to option (ii)-
\(\begin {array}{l}{5 Cl_2 + 10e^- \rightarrow 10Cl^-}\\{Cl_2 + 12OH^- \rightarrow 2Cl{O_3}^- + 6H_2O + 10e^-}\\\hline 6Cl_2 + 12OH^- \rightarrow 10Cl^- + 2Cl{O_3}^- + 6H_2O\end{array}\)
or
\(3Cl_2 + 6OH^- \rightarrow 5Cl^- + Cl{O_3}^- + 3H_2O\) ...(iii)
Hence equation (iii) is a balance chemical equation.
