\(n_{NaOH}=0.35\cdot0.1=0.035\left(mol\right)\)
\(n_{AlCl_3}=0.1\cdot0.1=0.01\left(mol\right)\)
\(3NaOH+AlCl_3\rightarrow3NaCl+Al\left(OH\right)_3\)
\(0.03..........0.01.........................0.01\)
\(n_{NaOH\left(cl\right)}=0.035-0.03=0.005\left(mol\right)\)
\(NaOH+Al\left(OH\right)_3\rightarrow NaAlO_2+2H_2O\)
\(0.005.........0.005\)
\(n_{Al\left(OH\right)_3\left(cl\right)}=0.01-0.005=0.005\left(mol\right)\)
\(m_{Al\left(OH\right)_3}=0.005\cdot78=0.39\left(g\right)\)