`CuCO_(3)` was strongly heated to obtain a residue A and gas B. The residue obtained was treated with a salt of sodium 'X' and oxide Y, which produced a blue colored glassy compound C on heating in oxidising flame. The same combination of x and Y gave a green colored glassy compound D when `Cr_(2)(SO_(4))_(3)` was heated with them in oxidizing flame. Match the following accordingly :

Answer

A, B, C, D

Explanation

`CuCO_(3) overset(Delta)to underset((A))(CuO)darr+underset((B))(CO_(2))uarr`
`CuO+underset("Borax bead")ubrace(overset((X))(NaBO_(2))+B_(2)O_(3))to underset((C )"Blue bead")ubrace(Cu(BO_(2))_(2))+NaBO_(2)`
`Cr_(2)(SO_(4))_(3) underset("Bead test")overset("Borax")to ` Green colored metaborate