In Kjeldahl's method for estimation of nitrogen,$CuSO_4$ acts as :

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.

$0.5 \ g$ 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:

Which formula is used in the Kjeldahl method for the estimation of nitrogen?

During the estimation of nitrogen present in an organic compound by the Kjeldahl method,the ammonia evolved from $0.5 \ g$ of the compound neutralized $10 \ mL$ of $1 \ M$ $H_{2}SO_{4}$. Find the percentage of nitrogen in the compound. (in $\%$)

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	$(t)$. $BaSO_4$