What is the formula for calculating the percentage of nitrogen in the Dumas method?

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 ....

$1.4 \ g$ of an organic compound was digested according to Kjeldahl's method and the ammonia evolved was absorbed in $60 \ mL$ of $M/10 \ H_2SO_4$ solution. The excess sulphuric acid required $20 \ mL$ of $M/10 \ NaOH$ solution for neutralization. The percentage of nitrogen in the compound is

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

How much $\%$ sulphur is present in an organic compound if on analysis $0.53 \ g$ of this compound gives $1.158 \ g$ of $BaSO_4$ (in $\%$)?

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