What Is the Molarity of a Potassium Triiodide Solution,KI₃(aq),if 30

Multiple Choice

What is the molarity of a potassium triiodide solution,KI₃(aq) ,if 30.00 mL of the solution is required to completely react with 25.00 mL of a 0.200 mol L^-1 thiosulfate solution,K₂S₂O₃(aq) ? The chemical equation for the reaction is
2 S₂O₃^2-(aq) + I₃^-(aq) → S₄O₆^2-(aq) + 3 I^-(aq)

A) 0.0833 mol L^-1
B) 0.120 mol L^-1
C) 0.167 mol L^-1
D) 0.333 mol L^-1