Is aluminium hyroxide an alkali?

Dear Student,

No, Al(OH)₃ is amphoteric as it reacts with both acids as well as bases. 
$$\begin{gathered} \mathrm{Al}(\mathrm{OH}{)}_3 +\hspace{0.17em}3\mathrm{HCl} \to {\mathrm{AlCl}}_3 + 3{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Al}(\mathrm{OH}{)}_3 + \mathrm{NaOH}\hspace{0.17em}\to {\mathrm{NaAlO}}_2 + 2{\mathrm{H}}_2\mathrm{O} \end{gathered}$$