1.

Borax [Na_(2)B_(4)O_(7).10H_(2)O] when heated on platinum loop it gives a dark transparent glass like bead. The hot bead is dipped in the salt till it reacts with transition metal oxide. It produces characteristic bead of meta borate. {:("Colour of the bead","lon"),("(a) Blue green or light blue",Cu^(+2)),("(b) Yellow",Fe^(+2)or Fe^(+3)),("(c) Green",Cr^(+3)),("(d) Violet",Mn^(+2)),("(e) Dark blue",Co^(+2)),("(f) Brown",Ni^(+2)):} Glassy bead is of

Answer»

`B_(2)O_(3)+NaBO_(2)`
`Na_(3)BO_(3)`
`Na_(2)B_(4)O_(7)`
`SiO_(2)`

Answer :A


Discussion

No Comment Found