Sodium fusion extract of which compound gives Prussian blue colour with $FeSO_4$?

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

Give the answers for the Lassaigne test:
$(i)$ If nitrogen and sulphur are both present,what observation is observed?
$(ii)$ If bromine is present,what is the observation?
$(iii)$ In the Lassaigne extract,if black precipitates are not obtained upon adding $CH_3COOH$ and lead acetate,what does this indicate?
$(iv)$ What is the reason for adding $FeSO_4$ to the Lassaigne extract?
$(v)$ Why is the Prussian blue colour observed?
$(vi)$ What does the violet colour with sodium nitroprusside in the Lassaigne extract indicate?

The formula of the purple colour formed in $Lassaigne's$ test for sulphur using sodium nitroprusside is ......

During the detection of phosphorus in an organic compound,a yellow precipitate is formed due to the formation of:

Give the chemical reaction for the detection of nitrogen in an organic compound using the Lassaigne's test.