In the titration of sodium thiosulphate and iodine, the equivalent mass of the former is equal to

The equivalent weight is the gram molecular weight divided by the number of electrons lost or gained by each molecule.

The reaction is $2{\mathrm{S}}_2{\mathrm{O}}_3^{2-}+{\mathrm{I}}_2\to {\mathrm{S}}_4{\mathrm{O}}_6^{2-}+2{\mathrm{I}}^{-}$ Equivalent mass= Molar mass