\(n_{H_2SO_4}=0.25\cdot1.5=0.375\left(mol\right)\)
\(Al_2O_3+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2O\)
\(0.125.......0.375............0.125\)
\(a.\)
\(m_{Al_2O_3}=0.125\cdot102=12.75\left(g\right)\)
\(b.\)
\(m_{Al_2\left(SO_4\right)_3}=0.125\cdot342=42.75\left(g\right)\)
\(c.\)
\(CM_{Al_2\left(SO_4\right)_3}=\dfrac{0.125}{0.25}=0.5\left(M\right)\)