Final answer:
Without the balanced chemical equation for the reaction between Na₂S₂O₃ and Cl₂, we cannot accurately determine the number of moles of Na₂S₂O₃ required to react with 0.4 moles of Cl₂.
Step-by-step explanation:
To determine how many moles of Na₂S₂O₃ are needed to react with 0.4 moles of Cl₂, we need the balanced chemical equation that describes the reaction between sodium thiosulfate (Na₂S₂O₃) and chlorine (Cl₂). Unfortunately, the provided information does not include this specific reaction, so we are missing vital details necessary to calculate the stoichiometry and provide an accurate answer.
If we had the balanced equation, we could use the coefficients in that equation to determine the mole ratio between Na₂S₂O₃ and Cl₂. We would then multiply 0.4 moles of Cl₂ by this stoichiometric ratio to find the number of moles of Na₂S₂O₃ needed for the reaction.