Al2O3 (aluminium oxide) was leached with alkali to get Na[Al(OH)4](X) (sodium aluminate). The solution of sodium aluminate when passed through gas Y, i.e. carbon dioxide (CO2) forms (Al2O3⋅xH2O)(Z). Complete reactions are as follows Aluminium oxideAl2O3+Sodium hydroxide2NaOH(aq)+3H2O(l)⟶2Na[(X)Al(OH)4](aq)(Z)Al2O3⋅xH2O+CO→2(Y)+Sodium bicarbonate2NaHCO3 Hence, X=Na[Al(OH)4]Y=CO2Z=Al2O3⋅xH2O