\(n_{Al_2\left(SO_4\right)_3}=\dfrac{10,26}{342}=0,03\left(mol\right)\)
\(\Rightarrow\left[Al^{3+}\right]=2C_{M\left(Al_2\left(SO_4\right)_3\right)}=\dfrac{2.0,03}{0,15}=0,4M\)
\(\left[SO_4^{2-}\right]=3C_{M\left(Al_2\left(SO_4\right)_3\right)}=\dfrac{3.0,03}{0,15}=0,6M\)