$n_{Al}=5,4/27=0,2mol$
$2Al+3H_SO_4\to Al_2(SO_4)_3+3H_2↑$
$\text{a/Theo pt :}$
$n_{H_2SO_4}=3/2.n_{Al}=3/2.0,2=0,3mol$
$⇒m_{H_2SO_4}=0,3.98=29,4g$
$⇒m_{ddH_2SO_4}=\dfrac{29,4}{10\%}=294g$
$\text{b/Theo pt :}$
$n_{H_2}=3/2.n_{Al}=3/2.0,2=0,3mol$
$⇒V_{H_2}=0,3.22,4=6,72l$