Chemistry 5070 · O Level · Formulae

Formulae — practice question

A compound is made up of $70\%$ iron by mass and $30\%$ oxygen by mass. What is the empirical formula of this compound? [$A_r$: O, $16$; Fe, $56$]

  • A$\text{FeO}$
  • B$\text{Fe}_2\text{O}_3$
  • C$\text{Fe}_3\text{O}_2$
  • D$\text{Fe}_3\text{O}_4$

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