In iodometric estimation of ${\mathrm{Cu}}^{2+}$ ion the following reactions took place

$$\begin{gathered} 2{\mathrm{Cu}}^{2+}+4\mathrm{I}⟶{\mathrm{Cu}}_2{\mathrm{I}}_2+{\mathrm{I}}_2 \\ {\mathrm{I}}_2+2{\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3⟶2\mathrm{NaI}+{\mathrm{Na}}_2{\mathrm{S}}_4{\mathrm{O}}_6 \end{gathered}$$

If 100 mL of ${\mathrm{CuSO}}_4$solution added to excess $\mathrm{KI}$ requires 50 mL of $0.2 \mathrm{M} \mathrm{Na},{\mathrm{S}}_2{\mathrm{O}}_3$ the molarity of ${\mathrm{CuSO}}_4$ solution is: