$0.2595 \ g$ of an organic substance in a quantitative analysis yielded $0.35 \ g$ of barium sulphate. The percentage of sulphur in the substance is $...$

$0.1 \ g$ of an organic compound was analyzed by the Kjeldahl method. The $NH_3$ produced was absorbed in $30 \ mL$ of $N/5$ $H_2SO_4$. The remaining acid required $20 \ mL$ of $N/10$ $NaOH$ for neutralization. Calculate the percentage of nitrogen in the organic compound.

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

$0.53 \ g$ of an organic compound $(x)$ when heated with excess of nitric acid (concentrated) and then with silver nitrate gave $0.75 \ g$ of silver bromide precipitate. $1.0 \ g$ of $(x)$ gave $1.32 \ g$ of $CO_2$ gas on combustion. The percentage of hydrogen in the compound $(x)$ is . . . . . . $\%$. [Nearest Integer]
[Given : Molar mass in $g \ mol^{-1} H : 1, C : 12, Br : 80, Ag : 108, O : 16$; Compound $(x) : C_xH_yBr_z$] (in $\%$)

On complete combustion,$0.30 \, g$ of an organic compound gave $0.20 \, g$ of carbon dioxide and $0.10 \, g$ of water. The percentage of carbon in the given organic compound is $.....$ (Nearest Integer).

In Dumas method for the estimation of $N_2$,the sample is heated with copper oxide and the gas evolved is passed over :