Explanation:
1) Amphoteric substances can react both like an acid or a base depending if they are in presence of a base or an acid.
Zinc hydroxide (Zn(OH)2):
In acid: [tex]Zn(OH)_2 + 2 HCl \longrightarrow ZnCl_2 + 2 H_2O [/tex]
In base: [tex]Zn(OH)_2 + 2 NaOH \longrightarrow Na_2[Zn(OH)_4][/tex]
Aluminium hydroxide (Al(OH)3)
In acid: [tex]Al(OH)_3 + 3 HCl \longrightarrow AlCl_3 + 3 H_2O [/tex]
In base: [tex]Al(OH)_3 + NaOH \longrightarrow Na[Al(OH)_4][/tex]
2) Reactions
a) [tex] 2 NH_3 + Cu^{2+} + 2 H_2O \longrightarrow 2 NH_4^+ + Cu(OH)_2[/tex]
[tex] 3 NH_3 + Fe^{3+} + 3 H_2O \longrightarrow 3 NH_4^+ + Fe(OH)_3[/tex]
b) [tex] 2 NH_3 + Zn^{2+} + 2 H_2O \longrightarrow 2 NH_4^+ + Zn(OH)_2[/tex]
[tex] 3 NH_3 + Al^{3+} + 3 H_2O \longrightarrow 3 NH_4^+ + Al(OH)_3[/tex]
