Which method is used for the quantitative estimation of nitrogen in an organic compound?

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 ....

In the estimation of sulphur by Carius method,$0.468 \,g$ of an organic sulphur compound afforded $0.668 \,g$ of barium sulphate. Find out the percentage of sulphur in the given compound. (in $\%$)

During the quantitative estimation of $C$ and $H$,the $CO_2$ produced is absorbed in which of the following?

In Dumas's method for estimation of nitrogen,$0.25 \, g$ of an organic compound gave $40 \, mL$ of nitrogen collected at $300 \, K$ temperature and $725 \, mm$ pressure. If the aqueous tension at $300 \, K$ is $25 \, mm,$ the percentage of nitrogen in the compound is

Which formula is used in the Kjeldahl method for the estimation of nitrogen?