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 ?

Answer

(i)(a)When borax is heated strongly, a transparent glassy bead which consists of sodium metaborate `(NaBO_(2))` and boric anhydride is formed.
`Na_(2)B_(4)O_(7). 10H_(2)Ooverset(Delta)toNa_(2)B_(4)O_(7)+10H_(2)O uar r`
`Na_(2)B_(4)O_(7)overset(740^(@)C)to 2NaBO_(2)+underset("borax bead")(B_(2)O_(3))`
(b)Boric act acts as a weak Lewis acid by accepting a hydroxide ion of water and releasing a proton into the solution.
`(##RES_INO_CHM_XI_C06_E01_016_A01##)`
( c)Dihydrogen is evolved.
`2Al(s)+2NaOH(aq)+6H_(2)O(l)to2Na^(+)[Al(OH)_(4)]^(-)(aq)+3H_(2)(g)`
(d)`BF_(3)` being a lewis acid accepts a pair of electrons from `NH_(3)` to form the corresponding complex.
`(##RES_INO_CHM_XI_C06_E01_016_A02##)`
(ii)`ZnO` is reduced to zinc metal.
`ZnO+CO to Zn+CO_(2)`