Chemistry - Complete Pblock- Question with Solution | TestHub

On running sodium thiosulphate solution into an iodine solution (in KI solution), the reddish-brown colour is gradually discharged through yellow to colourless.
${\mathrm{I}}_2+2{\mathrm{e}}^{-}\to 2{\mathrm{I}}^{-}$
$2\mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_2{\mathrm{O}}_3\to \mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_4{\mathrm{O}}_6+2\mathrm{N}{\mathrm{a}}^{+}+2{\mathrm{e}}^{-}$
$2\mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_2{\mathrm{O}}_3+{\mathrm{I}}_2\to \mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_4{\mathrm{O}}_6+2\mathrm{N}{\mathrm{a}}^{+}{\mathrm{I}}^{-}$