Write the chemical reactions associated with the 'borax' best 'test' of cobalt `(II)` oxide.

Explanation

When borax is heated, a colourless glassy bead is formed of the following composition :
`Na_(2)B_(4)O_(7).10 H_(2)O overset(Delta)rarr Na_(2)B_(4) O_(7)+10 H_(2)O`
`Na_(2)B_(4)O_(7) overset(Delta)rarr 2NaBO_(2) + B_(2)O_(3)`
`Co(II) "salt" overset(Delta)rarr CoO + "Some gas"`
`CoO +B_(2)O_(3) overset(Delta)rarr Co(BO_(2))_(2)`
Blue-coloured bead of cobalt metaborate is formed.