$n_{H_2}=8,96/22,4=0,4mol$
$PTHH :$
$Mg+H_2SO_4\to MgSO_4+H_2↑$
$Zn+H_2SO_4\to ZnSO_4+H_2↑$
$\text{a/Gọi}$ $n_{Mg}=a;n_{Zn}=b$
$\text{Ta có :}$
$m_{hh}=24a+65b=17,8g$
$n_{H_2}=a+b=0,4mol$
$\text{Ta có hpt :}$
$\left\{\begin{matrix}
24a+65b=17,8 & \\
a+b=0,4 &
\end{matrix}\right.$
$⇔\left\{\begin{matrix}
a=0,2 & \\
b=0,2 &
\end{matrix}\right.$
$⇒m_{Mg}=0,2.24=4,8g$
$m_{Zn}=17,8-4,8=13g$
$b/m_{muối}=m_{MgSO_4}+m_{ZnSO_4}=120×0,2+161×0,2=56,2g$
$c/n_{BaSO_4}=n_{MgSO_4}+n_{ZnSO_4}=0,2+0,2=0,4mol$
$⇒m_{BaSO_4}=0,4.232=92,8g$