In the Lassaigne's test,the Prussian blue precipitate is formed due to the formation of which compound?

The compound that does not give a positive test for nitrogen in Lassaigne's test is

The Kjeldahl's method for the estimation of nitrogen can be used to estimate the amount of nitrogen in which one of the following compounds?

In the Lassaigne's test for the detection of sulfur,which substance is responsible for the formation of black precipitates?

Match the List-$I$ with List-$II$:

List-$I$ (Reagent)	List-$II$ (Functional Group detected)
$A$. Sodium bicarbonate solution	$I$. Double bond/unsaturation
$B$. Neutral ferric chloride	$II$. Carboxylic acid
$C$. Ceric ammonium nitrate	$III$. Phenolic $-OH$
$D$. Alkaline $KMnO_4$	$IV$. Alcoholic $-OH$

Choose the correct answer from the options given below:

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?