In the estimation of nitrogen by Kjeldahl's method,$2.8 \ g$ of an organic compound required $20 \ mmol$ of $H_2SO_4$ for the complete neutralisation of $NH_3$ gas evolved. The percentage of nitrogen in the sample is?........$\%$

In a Carius tube,an organic compound '$X$' is treated with sodium peroxide to form a mineral acid '$Y$'. The solution of $BaCl_2$ is added to '$Y$' to form a precipitate '$Z$'. '$Z$' is used for the quantitative estimation of an extra element. '$X$' could be:

In Kjeldahl's method for the estimation of nitrogen,the formula used is

Match Column-$I$ and Column-$II$ with the correct relation:

Column-$I$	Column-$II$
$(i)$. Estimation of carbon and hydrogen	$(p)$. $AgX$
$(ii)$. Estimation of nitrogen	$(q)$. $CO_2$ and $H_2O$
$(iii)$. Estimation of halogen	$(r)$. $N_2$
$(iv)$. Estimation of sulphur	$(s)$. $Mg_2P_2O_7$
$(v)$. Estimation of phosphorus	$(t)$. $BaSO_4$

$29.5 \, mg$ 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?

In $DNA$ and $RNA,$ nitrogen atoms are present in the ring system. Can the Kjeldahl method be used for the estimation of nitrogen present in these?