$$\begin{gathered} \left(\mathrm{A}\right):2{\mathrm{S}}_2{\mathrm{O}}_{3\left(\mathrm{aq}\right)}^{-2}+{\mathrm{I}}_{2\left(\mathrm{S}\right)}\to {\mathrm{S}}_4{\mathrm{O}}_{6\left(\mathrm{aq}\right)}^{-2}+2{\mathrm{I}}_{\left(\mathrm{aq}\right)}^{-} ; \\ \left(\mathrm{B}\right): {\mathrm{S}}_2{\mathrm{O}}_{3\left(\mathrm{aq}\right)}^{-2}+2{\mathrm{Br}}_{2\left(\mathrm{l}\right)}+5{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}\to 2{\mathrm{SO}}_{4\left(\mathrm{aq}\right)}^{-2}+4{\mathrm{Br}}_{\left(\mathrm{aq}\right)}^{-}+10{\mathrm{H}}_{\left(\mathrm{aq}\right)}^{+} \end{gathered}$$

Different products are given by thiosulphate in (A) and (B) . This is best explained by the fact that