Nitrogen can be estimated by Kjeldahl's method for which of the following compounds?

Lassaigne's test for nitrogen is negative for which compound?

In the preparation of sodium fusion extract,the purpose of fusing organic compound with a piece of sodium metal is to

The organic compound that gives the following qualitative analysis is:

Test	Inference
$a$. Dil. $HCl$	Insoluble
$b$. $NaOH$ solution	Soluble
$c$. $Br_2/\text{water}$	Decolourization

Sodium extract is heated with concentrated $HNO_3$ before testing for halogens because

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.