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

$0.5 \ g$ of an organic compound containing phosphorus was heated with conc. $HNO_3$ in a Carius tube. The phosphoric acid thus formed was precipitated with magnesia mixture $[MgNH_4PO_4]$,which on ignition gave a residue of $1.0 \ g$ of magnesium pyrophosphate $(Mg_2P_2O_7)$. The percentage of phosphorus in the organic compound is:

The number of moles of $CuO$ that will be utilized in the Dumas method for the estimation of nitrogen in a sample of $57.5 \ g$ of $N,N$-dimethylaminopentane is $..... \times 10^{-2}$. (Nearest integer)

Dumas method involves the determination of nitrogen content in the organic compound in the form of

Fill in the blanks:
$(1)$ ........... solution is added to produce the precipitate of $BaSO_4$ in the estimation of sulphur.
$(2)$ .......... and .... precipitate will be produced by the estimation of phosphorus.
$(3)$ How many elements are estimated in organic compounds?
$(4)$ ......... gas is produced in the Dumas method,but ....... gas is produced in the Kjeldahl's method.

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