Which of the following statement(s) is/are correct?

Options

A. The oxide, `B_(2)O_(3)` and `B(OH)_(3)` are acidic
B. The halides of `B`(except `BF_(3)`) and `Si` are hydrolysed.
C. The hydrides of `B` and `Si` are volatile, spontaneously flammable and readily hydrolysed.
D. Aluminium hydride is a polymer, `(AIH_(3))_(n)`.

Answer

A, B, C, D

Explanation

(A)It is a acidic oxide and is anhydride of boric acid and it reacts with alkalies or bases to form borates.
`3Na_(2)O+B_(2)O_(3)to2Na_(3)BO_(3)`(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)+2H_(2)O(l)hArr[B(OH)_(4)]^(-)(aq)+H_(3)O^(+)(aq)`. , `pK=9.25`
(B)`BX_(3)` (except `BF_(3)`) get hydrolysed due to presence of vacant `p`-orbital and `SiX_(4)` get hydrolysed due to presence of vacant `d` -orbital.
( C)Controlled pyrolysis of dibrone leads to most of the higher boranes.
It catches fire spontaneously in air and explodes with `O_(2)`.Reaction with oxygen is extremely exothermic.
`B_(2)H_(6)+3O_(2)toB_(2)O_(3)+3H_(2)O` , `DeltaH=-2160 kJ mol^(-1)`
`Si_(2)H_(6)+(4+n)H_(2)O overset("trace of alkali")to 2SiO_(2)+nH_(2)O +7H_(2)`
(D)Aluminium hydride is a polymer due to formation of electron defecient bond `(Al-H---Al)`