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 0.300 M 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. 125 M
B) 0. 180 M
C) 0. 250 M
D) 0.500 M