The volume of nitrogen is measured by which apparatus in the Dumas method?

The presence of halogen in an organic compound is detected by:

An organic compound containing phosphorus on oxidation with $Na_2O_2$ gives a compound '$X$'. This '$X$' when boiled with $HNO_3$ followed by treatment with ammonium molybdate reagent gives a yellow precipitate '$Y$'. '$X$' and '$Y$' respectively are:

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 $C_6H_5CH_2COOH$

The Lassaigne's extract is boiled with conc. $HNO_3$ while testing for halogens. By doing so it

The fusion of sodium with an organic compound containing nitrogen gives mainly: