Which compound is formed by heating with nitric acid in the estimation of phosphorus in the Carius method?

What is $CHN$ analysis in organic estimation?

In sulphur estimation,$0.471 \ g$ of an organic compound gave $1.4439 \ g$ of barium sulphate. The percentage of sulphur in the compound is $.............$ (Nearest Integer) (Given: Atomic mass $Ba: 137 \ u, S: 32 \ u, O: 16 \ u$)

Which of the following substances cannot be analyzed using the Kjeldahl method for the estimation of nitrogen?

For the estimation of nitrogen,$1.4 \ g$ of an organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in $60 \ mL$ of $\frac{M}{10}$ sulphuric acid. The unreacted acid required $20 \ mL$ of $\frac{M}{10}$ sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound is .....$\%$

$0.2 \ g$ of an organic compound was subjected to estimation of nitrogen by Dumas method in which volume of $N_2$ evolved (at $STP$) was found to be $22.400 \ mL$. The percentage of nitrogen in the compound is $.......$. [nearest integer] (Given: Molar mass of $N_2$ is $28 \ g \ mol^{-1}$. Molar volume of $N_2$ at $STP$ : $22.4 \ L \ mol^{-1}$ )