1.

Which of the following salts is used in the bead test for basic radicals ?

Answer»

`Na(NH_(4))HPO_(4).4H_(2)O`
`Na_(2)HPO_(4)`
`(NH_(4))_(2)SO_(4).FeSO_(4).6H_(2)O`
`(NH_(3))_(2)HPO_4.4H_2O`

Solution :Microcosmic salt on HEATING produces a transparent bead of sodium metaphosphate `(NaPO_3).`
`Na(NH_(4))HPO_(4).4H_(2) overset(Delta)to NH_(3)+5H_(2)O+NaPO_(3)`
`NaPO_(3)` combines with certain metallic OXIDES to form coloured BEADS of the corresponding orthophosphates, e.g.,
`NaPO_(3)+CuO to underset(("Blue"))(CuNaPO_(4))`
Hence , microcosmic salt is sometimes USED in place of borax for performing borax bead TEST.


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