`"Colemanite" + Na_(2)CO_(3) overset("Fused")rarr (A) + (B) + CO_(2)`
`underset("Solution")((A)) + CO_(2) rarr(B) + Na_(2) CO_(3)`
`(B) + conc HCl rarr NaCl + underset("Acid")((C))`
`underset("Acid")((C)) +H_(2)O rarr underset("Acid")((D))`
`(D) overset("Strong heating")rarr (E)`
`(E) +CuSO_(4) overset("Heated") underset("inflame")rarr underset("Blue-coloured compound")((F))`.
Compound `(F)` is.

Options

A. `CuS`
B. `Cu_(2)O`
C. `CuSO_(3)`
D. `Cu(BO_(2)_(3)`

Answer

D

Explanation

`underset("Colemanite") (Ca_(2)B_(6) O_(11)) + 2Na_(2)CO_(3) overset("Fused") rarr underset(underset("metaborate")("Sodium"))(NaBO_(2)) + underset((B))(Na_(2)N_(4)O_(7))+ 2CO_(2)`
`underset((A))(NaBO_(2(aq))) + CO_(2) rarr underset((B))(Na_(2)B_(4)O_(7))+ Na_(2)CO_(3)`
`underset((B))(Na_(2)B_(4)O_(7)) + underset("Conc")(HCl) rarr NaCl + underset((C))(H_(2) B_(4) O_(7))`
`underset((C))(H_(2)B_(4)O_(7)) + 5H_(2)O rarr underset((D))(4H_(3)BO_(3))`
`underset((D))(2H_(3)BO_(3)) overset("Strong") underset("heating") rarr underset((E))(B_(2)O_(3)) + 3H_(2)O`
`underset((E))(B_(2)O_(3)) + CuSO_(4) overset("Heated in flame")rarr underset((F) "Blue coloured compound") (Cu(BO_(2))_(3))`.
`Cu(BO_(2)_(3)`.