The sodium fusion extract is boiled with concentrated nitric acid while testing for halogens. By doing so,it

Three students,Manish,Ramesh,and Rajni were determining the extra elements present in an organic compound given by their teacher. They prepared the Lassaigne's extract $(L.E.)$ independently by the fusion of the compound with sodium metal. Then they added solid $FeSO_4$ and dilute sulphuric acid to a part of the Lassaigne's extract. Manish and Rajni obtained prussian blue colour,but Ramesh got red colour.
Ramesh repeated the test with the same Lassaigne's extract,but again got red colour only. They were surprised and went to their teacher and told him about their observation. Teacher asked them to think over the reason for this. Can you help them by giving the reason for this observation? Also,write the chemical equations to explain the formation of compounds of different colours.

Match column $-I$ and column $-II$ with the correct relation:

Column $-I$	Column $-II$
$(i).$ Lassaigne's test	$(a).$ By sodium peroxide
$(ii).$ Test for nitrogen	$(b).$ Acidify with acetic acid
$(iii).$ Test for sulphur	$(c).$ Acidify with conc. sulphuric acid
$(iv).$ Test for phosphorus	$(d).$ Fusion with sodium

In the detection test of nitrogen,the Prussian blue colour is due to which compound?

Match the organic compounds in column $I$ with the Lassaigne's test results in column $II$ appropriately.

Column $I$	Column $II$
$A$. Aniline	$i$. Red colour with $FeCl_3$
$B$. Benzene sulfonic acid	$ii$. Violet colour with sodium nitroprusside
$C$. Thiourea	$iii$. Blue colour with hot and acidic solution of $FeSO_4$

Beilstein test is used for the detection of which one of the following elements?