Ta có: $n_{SO2}$ = 6,72/22,4 = 0,3 ( mol)
PT: Mg + 2H2SO4 ---> MgSO4 + SO2 + 2H2O
x 2x x (mol)
Zn + 2H2SO4 ---> ZnSO4 + SO2 + 2H2O
y 2y y (mol)
Ta có HPT: $\left \{ {{x+y=0,3} \atop {24x+ 65y=11,3}} \right.$
<=> $\left \{ {{x=0,2} \atop {y=0,1}} \right.$
a) Ta có: $m_{Mg}$ = 24*0,2 = 4,8 g
=>%$m_{Mg}$ = $\frac{4,8}{11,3}$.100% ≈ 42,48%
=>%$m_{Zn}$ = 100% - 42,48% = 57,52%
b) $V_{H2SO4}$ = (2.0,2 + 2.0,1).22,4 = 13,44 l