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

In an estimation of sulphur by Carius method, $0.2 \text{ g}$ of the substance gave $0.6 \text{ g}$ of $BaSO_4$. The percentage of sulphur in the substance is . . . . . . %. (Given molar mass in $\text{g mol}^{-1}$: $S = 32$, $BaSO_4 = 233$)

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.

Describe the principle and reactions involved in the estimation of oxygen in an organic compound.

In the Kjeldahl method,$0.35 \ g$ of an organic compound produces ammonia,which is absorbed in $100 \ mL$ of $0.1 \ M \ H_2SO_4$. The excess $H_2SO_4$ requires $154 \ mL$ of $0.1 \ M \ NaOH$ for titration. Calculate the percentage of nitrogen in the compound. (Given atomic masses: $C=12, H=1, O=16, N=14, S=32$)

Explain the Carius method and its principle for the estimation of phosphorus in an organic compound.