Em sửa đề là : 56(g) nhé
\(n_{Fe}=\dfrac{56}{56}=1\left(mol\right)\)
\(3Fe+2O_2\underrightarrow{t^0}Fe_3O_4\)
\(1........\dfrac{2}{3}..........\dfrac{1}{3}\)
\(m_{Fe_3O_4}=\dfrac{1}{3}\cdot232=77.33\left(g\right)\)
\(V_{O_2}=\dfrac{2}{3}\cdot22.4=14.93\left(l\right)\)