\(n_{Al}=\dfrac{5.4}{27}=0.2\left(mol\right)\)
\(n_{H_2SO_4}=\dfrac{49}{98}=0.5\left(mol\right)\)
\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)
\(0.2........0.3.................................0.3\)
\(m_{H_2SO_4\left(dư\right)}=\left(0.5-0.3\right)\cdot98=19.6\left(g\right)\)
\(V_{H_2}=0.3\cdot22.4=6.72\left(l\right)\)