Here X, Y and Z are

• Aluminum is heated with nitrogen gas to form aluminum nitride (AlN).

$2\mathrm{Al}+\underset{\mathrm{X}}{{\mathrm{N}}_2}\stackrel{∆}{\to }\underset{\mathrm{Y}}{2\mathrm{AlN}}$

• AlN treated with water to form aluminum hydroxide and liberates ammonia gas.

$\mathrm{AlN}+3{\mathrm{H}}_2\mathrm{O}\to \underset{\mathrm{Z}}{\mathrm{Al}{\left(\mathrm{OH}\right)}_3}+{\mathrm{NH}}_3\uparrow$