What happens when
(a) Borax is heated strongly,
(b) Boric acid is added to water,
(c) Aluminium is treated with dilute NaOH,
(d) `BF_(3)` is reacted with ammonia ?

Explanation

(a) When powdered borax is heated strongly in the flame of bunsen burner, it forms a colourless transparent glassy (glass-like) bead made of sodium meta borate and boric anhydride.

(b) It dissovles in water as it is electron deficient in nature.
`B(OH)_(3)+H-OHrarr[B(OH)_(4)]^(-)+H^(+)`
`[H_(3)BO_(3)]`
( c) Aluminium dissovles in NaOH solution to form a soluble complex, liberating hydrogen gas.
`2Al(s)+2NaOH(aq)+6H_(2)O(l)rarr2Na^(+)[Al(OH)_(4)]^(-)(aq)+3H_(2)(g)`
Soluble complex
(d) `BF_(3)` (Lewis acid in nature). forms an addition compound with `NH_(3)` (Lewis base in nature).