Action of Acids

(i) Boron does not react with non oxidizing acids, however, it dissolves in nitric acid to form boric acids.

(ii) Al, Ga and In dissolve in acids forming their trivalent cations; however, Al and Ga become passive due to the formation of protective film of oxides.

(iii) Thallium dissolves in acids forming univalent cation and becomes passive in HCl due to the formation of water insoluble TICl.

Action of Alkalies

(i) Boron dissolves only in fused alkalies,

2B + 6NaOH (fused) → 2Na₃BO₃ + 3H₂

(ii) Al and Ga dissolves in fused as well as in aqueous alkalies,

2Al + 2 NaOH + 2H₂O → 2NaAl O₂ + 3H₂

(iii) Indium remains unaffected in alkalies even on heating.