How is boron obtained from borax ? Give the chemical reactions involved. Draw the structure of `B_(2)H_(6)` and give its reaction with `HCl`.

Explanation

`underset("Borax")(Na_(2)B_(4)O_(7))+ underset("Hot and conc")(H_(2)So_(4)) + 5H_(2)O rarr Na_(2)SO_(4) + underset("Boric acid")(4H_(3)BO_(3))`
`2H_(3)BO_(3) overset("Red heat")rarr underset("Boric oxide") (B_(2)O_(3))+ 3H_(2) O`
`B_(2)O_(3) +3Mg overset(Delta)rarr 2B +3MgO`

with dry `HCl rarr B_(2)H_(6)` reacts to evolve `H_(2)` gas :
`B_(2)H_(6) + HCl rarr B_(2) H_(5)Cl + H_(2) uarr`.