\(n_{Mg}=2x\left(mol\right),n_{Fe}=x\left(mol\right)\)
\(n_{HCl}=0.2\cdot0.45=0.9\left(mol\right)\)
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(n_{HCl}=2\cdot2x+2\cdot x=0.9\left(mol\right)\)
\(\Rightarrow x=0.15\)
\(m_{hh}=0.3\cdot24+0.15\cdot56=15.6\left(g\right)\)
\(V_{H_2}=0.45\cdot22.4=10.08\left(l\right)\)