In the estimation of phosphorus in an organic compound,phosphorus is $NOT$ weighed in the form of which of the following substances?

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

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 $\%$)

$29.5 \, mg$ of an organic compound containing nitrogen was digested according to Kjeldahl's method and the evolved ammonia was absorbed in $20 \, mL$ of $0.1 \, M \, HCl$ solution. The excess acid required $15 \, mL$ of $0.1 \, M \, NaOH$ solution for complete neutralization. What is the percentage of nitrogen in the compound?

$0.25 \ g$ of an organic compound $A$ containing carbon,hydrogen,and oxygen was analysed using the combustion method. The increase in mass of the $CaCl_2$ tube and the potash bulb at the end of the experiment was found to be $0.15 \ g$ and $0.1837 \ g$,respectively. The percentage of oxygen in compound $A$ is $.... \%$. (Nearest integer)
(Given: molar mass in $g \ mol^{-1}$,$H: 1, C: 12, O: 16$)

Explain the Carius method and its principle for the estimation of halogen elements.