In the $Dumas$ method,the nitrogen-containing organic compound is first heated with which of the following?

In $Duma's$ method of estimation of nitrogen,$0.35 \ g$ of an organic compound gave $55 \ mL$ of nitrogen collected at $300 \ K$ temperature and $715 \ mm$ pressure. The percentage of nitrogen in the compound is (aqueous tension at $300 \ K = 15 \ mm$). (in $.45$)

$A$ 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 of 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.

$x \ mg$ of an organic compound was analysed by the Kjeldahl method. The ammonia evolved was absorbed in $50 \ mL$ of $0.5 \ M \ H_2SO_4$. The unused acid required $60 \ mL$ of $0.5 \ M \ NaOH$ solution for complete neutralization. If the percentage of nitrogen in the compound is $56$,the value of $x$ is:

Which method uses an instrument called a nitrometer?