How many moles of FeO are needed to produce 1 mole of Fe3O4?

Answer 1

Start by writing a balanced reaction. For this, you can use 3FeO + 0.5O₂ -> Fe₃O₄. This is not the most technical way of writhing this reaction, but it works for this question.

Since the FeO has a coefficient of 3, you need 3 moles of FeO to produce 1 mole of Fe₃O₄.