a)\(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)
\(n_{Mg}=\dfrac{7,2}{24}=0,3mol\)
\(\rightarrow0,3molH_2\)\(\rightarrow V_{H2}=0,3.22,4=6,72l\)
b)\(H_2+Fe_2O_3\rightarrow3H_2O+2Fe\)
\(n_{Fe2O3}=\dfrac{19,2}{160}=0,12mol\)
\(\rightarrow0,24molFe\rightarrow m_{Fe}=0,24.56=13,44gam\)