\(a,3Fe+2O_2\rightarrow\left(t^o\right)Fe_3O_4\\ n_{Fe}=\dfrac{5,6}{56}=0,1\left(mol\right)\\ b,n_{Fe_3O_4}=\dfrac{1}{3}.0,1=\dfrac{1}{30}\left(mol\right)\\ a=m_{Fe_3O_4}=\dfrac{232}{30}=\dfrac{116}{15}\left(g\right)\\ c,n_{O_2}=\dfrac{2}{3}.0,1=\dfrac{1}{15}\left(mol\right)\\ V=V_{O_2\left(đkc\right)}=\dfrac{1}{15}.24,79=1,65266667\left(l\right)\)