In the estimation of sulphur in an organic compound,upon treatment with concentrated $HNO_3$,it is converted into:

Given below are two statements :
Statement $I$ : Kjeldahl method is applicable to estimate nitrogen in pyridine.
Statement $II$ : The nitrogen present in pyridine can easily be converted into ammonium sulphate in Kjeldahl method.
In the light of the above statements,choose the correct answer from the options given below.

$0.12 \ g$ of an organic compound '$X$' containing phosphorus on reacting with magnesia mixture gave $0.22 \ g$ of magnesium pyrophosphate $(Mg_2P_2O_7)$. The percentage of phosphorus in the compound '$X$' is (in $\%$)

Nitrogen present in an unknown organic compound was estimated by the Dumas method to be $17.7 \%$ by weight. The compound is very likely to be ....

The Kjeldahl method of nitrogen estimation fails for which of the following reaction products $?$
$(a)$ Nitrobenzene $\xrightarrow{Sn/HCl}$ Aniline
$(b)$ Benzonitrile $\xrightarrow{LiAlH_4}$ Benzylamine
$(c)$ Benzyl cyanide $\xrightarrow{(i) SnCl_2 + HCl, (ii) H_2O}$ Phenylacetaldehyde
$(d)$ Aniline $\xrightarrow{NaNO_2/HCl}$ Benzenediazonium chloride

While estimating the nitrogen present in an organic compound by Kjeldahl's method,the ammonia evolved from $0.25 \ g$ of the compound neutralized $2.5 \ mL$ of $2 \ M \ H_2SO_4$. The percentage of nitrogen present in the organic compound is $......$