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In Lassaigne's test for the detection of...

In Lassaigne's test for the detection of halogens, the sodium fusion extract is first boiled with concentrated nitric acid. This is

A

to remove silver halides

B

to decompose `Na_(2)S` and `NaCN`, if present

C

to dissolve `Ag_(2)S`

D

to dissolve AgCN, if formed

Text Solution

Verified by Experts

The correct Answer is:
B
To test halogens, it is necessary to rmove sodium cyanide and sodium sulphide from the sodium extract, if N and S are present. This is done by boiling sodium extract with conc. `HNO_(3)`.
`NaCN + HNO_(3) rarr NaNO_(3) + HCN uarr`
`Na_(2)S + 2HNO_(3) rarr 2NaNO_(3) + H_(2)S uarr`
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