Magnetite, which has the formula Fe₃O₄ , is comprised of iron(II) oxide and iron(III) oxide. What is the ratio of iron(II) ions to iron(III) ions in magnetite?

If your goal is to create ${\mathrm{Fe}}_3{\mathrm{O}}_4$ (a compound containing two ${\mathrm{Fe}}^{3+}$ and one ${\mathrm{Fe}}^{2+}$ ion) and your synthesis conditions allow you to ignore the oxidation or reduction of iron ions, you should begin with the 1:2 ratio that you indicated above. ${\mathrm{Fe}}_3{\mathrm{O}}_4$ is the finished product, and it contains one$\mathrm{Fe}\left(\mathrm{II}\right)$ and two $\mathrm{Fe} \left(\mathrm{III}\right)$.

$\stackrel{+2}{\mathrm{FeO}}\cdot \stackrel{+3}{{\mathrm{Fe}}_2{\mathrm{O}}_3}$

Hence, the correct option is B.