$n_{H_2}=\dfrac{8,96}{22,4}=0,4mol$
$PTHH :$
$2Al+6HCl\to 2AlCl_3+3H_2↑(1)$
$Zn+2HCl\to ZnCl_2+H_2↑(2)$
$Gọi\ n_{Al}=a;n_{Zn}=b(a,b>0)$
$\text{Ta có :}$
$m_{hh}=27a+65b=11,9g$
$n_{H_2}=1,5a+b=0,4mol$
$\text{Ta có hpt :}$
$\left\{\begin{matrix}
27a+65b=11,9 & \\
1,5a+b=0,4 &
\end{matrix}\right.$
$⇔\left\{\begin{matrix}
a=0,2 & \\
b=0,1 &
\end{matrix}\right.$
$⇒m_{Al}=0,2.27=5,4g$
$m_{Zn}=11,2-5,4=5,8g$
$\text{b.Theo pt (1) và (2) :}$
$n_{HCl}=3a+2b=0,8mol$
$⇒C_{M_{HCl}}=\dfrac{0,8}{0,4}=2M$