
(1) Al2O3+NaOH⟶"X"Na[Al(OH)4]
(2) Na[Al(OH)4]→"Y"CO2"Z"Al(OH)3 or Al2O3⋅xH2O
So, when Al2O3 was leached with alkali to get X. The solution of X on passing of gas Y, forms Z.
X,Y and Z respectively are
X:Na[Al(OH)4]
Y:CO2
Z:Al2O3⋅xH2O