a, \(3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)
b, \(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)
\(n_{Fe_3O_4}=\dfrac{1}{3}n_{Fe}=\dfrac{1}{15}\left(mol\right)\Rightarrow m_{Fe_3O_4}=\dfrac{1}{15}.232=\dfrac{232}{15}\left(g\right)\)
\(n_{O_2}=\dfrac{2}{3}n_{Fe}=\dfrac{2}{15}\left(mol\right)\Rightarrow V_{O_2}=\dfrac{2}{15}.22,4=\dfrac{224}{75}\left(l\right)\)