$1/$
$2Al+6HCl\to 2AlCl3+3H2↑$
$Zn+H2SO4\to ZnSO4+H2↑$
$Fe3O4+4H2\to 3Fe+4H2O$
$CuO+H2\overset{t^o}\to Cu+H2O$
$3CO+Fe2O3\overset{t^o}\to 2Fe+3CO2↑$
$Fe+2HCl\to FeCl_2+H2$
$3/$
$n_{H2}=6,72/22,4=0,3mol$
$a/$
$Fe_2O_3+3H_2\overset{t^o}\to 2Fe+3H_2O$
$b/$
Theo pt :
$n_{Fe}=2/3.n_{H2}=2/3.0,3=0,2mol$
$⇒m_{Fe}=0,2.56=11,2g$
$c/$
$n_{Fe_2O_3}=1/3.n_{H2}=1/3.0,3=0,1mol$
$⇒m_{Fe_2O_3}=0,1.160=16g$