In this reaction, NaOH is the limiting reagent
Mole of NaOH = 44.2 × 0.01L × 0.215M = 0.009503 mol
Al(NO3)3 + 3NaOH = Al(OH)3 + 3NaNO3
3 mole NaOH = 1 mole Al(OH)3 = 78g Al(OH)3
1 mole NaOH = 78/3 g Al(OH)3
0.009503 mole of NaOH = 78 × 0.009503/ 3 g Al(OH)3
= 0.25g Al(OH)3