A solution of 0.1M KMnO₄ is used for the reaction ${\mathrm{S}}_2{\mathrm{O}}_3^{-2}+2{\mathrm{MnO}}_4^{-}+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{MnO}}_2+{\mathrm{SO}}_4^{-2}+{\mathrm{OH}}^{-}$The volume of KMnO₄ required to react 0.158gm of Na₂S₂O₃ is (MW = 158)