How is the percentage of oxygen determined in the quantitative estimation of organic compounds?

Differentiate between the principle of estimation of nitrogen in an organic compound by $(i)$ Dumas method and $(ii)$ Kjeldahl's method.

Given below are two statements $I$ and $II.$
Statement $I :$ Dumas method is used for estimation of Nitrogen in an organic compound.
Statement $II :$ Dumas method involves the formation of ammonium sulphate by heating the organic compound with conc $H_2SO_4$. In the light of the above statements,choose the correct answer from the options given below.

Kjeldahl's method is used in the estimation of:

During the estimation of $C$ and $H$,the $H_2O$ produced is absorbed in which of the following?

$0.2 \ g$ of an organic compound was subjected to estimation of nitrogen by Dumas method in which volume of $N_2$ evolved (at $STP$) was found to be $22.400 \ mL$. The percentage of nitrogen in the compound is $.......$. [nearest integer] (Given: Molar mass of $N_2$ is $28 \ g \ mol^{-1}$. Molar volume of $N_2$ at $STP$ : $22.4 \ L \ mol^{-1}$ )