Which compounds are taken in the Kjeldahl's flask for the estimation of nitrogen?

Calculate the percentage of nitrogen in $0.25 \ g$ of an organic compound if $38 \ cm^3$ of $N_2$ gas is evolved at $300 \ K$ and $96 \ kPa$ pressure. (Given: $1 \ atm = 101.3 \ kPa$)

The transformation occurring in Dumas's method is given below:
$C_{2}H_{7}N + (2x + \frac{y}{2})CuO \rightarrow xCO_{2} + \frac{y}{2}H_{2}O + \frac{z}{2}N_{2} + (2x + \frac{y}{2})Cu$
The value of $y$ is ...... .(Integer answer)

$A$ sample of $0.125 \ g$ of an organic compound when analysed by Duma's method yields $22.78 \ mL$ of nitrogen gas collected over $KOH$ solution at $280 \ K$ and $759 \ mm \ Hg$. The percentage of nitrogen in the given organic compound is (Nearest integer).
$(a)$ The vapour pressure of water at $280 \ K$ is $14.2 \ mm \ Hg$
$(b)$ $R = 0.082 \ L \ atm \ K^{-1} \ mol^{-1}$

In the Carius method for the estimation of halogen,$0.15 \ g$ of an organic compound gave $0.12 \ g$ of $AgBr$. Find out the percentage of bromine in the compound (Molar mass of $AgBr = 188 \ g/mol$). (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 of the acid required $15 \ mL$ of $0.1 \ M \ NaOH$ solution for complete neutralization. The percentage of nitrogen in the compound is $..... \%$.