\(n_{Mg} = a ; n_{Al} = b ; n_{Fe} = c\\\Rightarrow 24a + 27b + 56c = 10,7(1)\\ Mg + 2HCl \to MgCl_2 + H_2\\ 2Al + 6HCl \to 2AlCl_3 + 3H_2\\ Fe + 2HCl \to FeCl_2 + H_2\\ n_{H_2} = a + 1,5b + c = \dfrac{7,84}{22,4} = 0,35(2)\\ n_{Cl_2} = \dfrac{4,48}{22,4}= 0,2(mol)\\ Mg + Cl_2 \xrightarrow{t^o} MgCl_2\\ 2Al + 3Cl_2 \xrightarrow{t^o} 2AlCl_3\\ \)
\(2Fe + 3Cl_2 \xrightarrow{t^o} 2FeCl_3\\ \dfrac{a+b+c}{a+1,5b+1,5c} = \dfrac{0,15}{0,2}(3) (1)(2)(3)\Rightarrow a = b = c = 0,1\\ \Rightarrow \%m_{Fe} = \dfrac{0,1.56}{10,7}.100\% = 52,34\%\)