What is the percent of iron and oxygen in iron(III) oxide?

Margaret wants to make an orange flavored drink by stirring powdered drink mix into a glass of water. she doesn't like drinks that have small clumps of powdered solid in them, so she wants the drink to be a perfect solution. what factors should margaret not consider when deciding how much powder to add to her glass of water?

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion

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