(a, b, c, d)

It is a acidic oxide and is anhydride of boric acid and it reacts with alkalies or bases to form borates.

3Na2O + B2O3 2Na3BO3 (sodium orthoborate)

It is a weak monobasic acid soluble in water and in aqueous solution the boron atom completes its octet by accepting OH– from water molecules:

B(OH)3(aq) + 2H2O( ) [B(OH)4]– (aq) + H3O+(aq). pK = 9.25.

BX3 (except BF3) get hydrolysed due to presence of vacant p-orbital and SiX4 get hydrolysed due to presence of vacant d-orbital.

Controlled pyrolysis of diborane leads to most of the higher boranes.

It catches fire spontaneously in air and explodes with O2. Reaction with oxygen is extremely exothermic.

B2H6 + 3O2 B2O3 + 3H2O Δ H = – 2160 kJ mol–1

Si2H6 + (4 + n) H2O 2SiO2 + nH2O + 7H2

Aluminium hydride is a polymer due to formation of electron defecient bond (Al —— H – – – Al).