In Kjeldahl's method of estimation of $N$,$CuSO_4$ acts as

What happens to the halogen when $AgNO_3$ is added to the Lassaigne solution acidified with $HNO_3$?

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

Identify the binary mixture$(s)$ that can be separated into individual compounds by differential extraction,as shown in the given scheme.
$(A)$ $C_6H_5OH$ and $C_6H_5COOH$
$(B)$ $C_6H_5COOH$ and $C_6H_5CH_2OH$
$(C)$ $C_6H_5CH_2OH$ and $C_6H_5OH$
$(D)$ $C_6H_5CH_2OH$ and $C_6H_5CH_2COOH$