In the Carius method for the estimation of halogens,$0.15 \, g$ of an organic compound gave $0.12 \, g$ of $AgBr$. Find the percentage of bromine in the compound. (in $\%$)

$1.2 \ g$ of an organic compound on Kjeldahlization liberates ammonia which consumes $30 \ cm^3$ of $1 \ N \ HCl$. The percentage of nitrogen in the organic compound is:

$0.25 \ g$ of an organic compound containing chlorine gave $0.40 \ g$ of silver chloride in Carius estimation. The percentage of chlorine present in the compound is $.....$ [in nearest integer].
(Given: Molar mass of $Ag$ is $108 \ g \ mol^{-1}$ and that of $Cl$ is $35.5 \ g \ mol^{-1}$)

$0.12 \ g$ 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 $\%$)

Describe the principle and reactions involved in the estimation of oxygen in an organic compound.

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