Quantitative estimatin of `C,H` and extra elements (e.g., N.S.P., and halogens) is carried out by Liebig's combustion, Carius, Dumas, and Kjeldahl's method.
Q. In Carius method for the quantitative estimation of sulphur, it is estimated by:

Options

A. `BaS`
B. `CaSO_4`
C. `BaSO_4`
D. `BaCl_2`

Answer

To solve the question regarding the quantitative estimation of sulfur using the Carius method, we can break it down into clear steps:

### Step-by-Step Solution:

1. **Understanding the Carius Method**: The Carius method is a technique used for the quantitative estimation of sulfur in organic compounds. It involves the oxidation of sulfur to a higher oxidation state.

2. **Oxidation of Sulfur**: In the Carius method, sulfur is oxidized to sulfuric acid (H₂SO₄). This is achieved by digesting the sample with fuming nitric acid (HNO₃). The fuming nitric acid provides the necessary oxidizing environment.

3. **Formation of Sulfuric Acid**: During the digestion process, the sulfur present in the organic compound is converted into sulfuric acid. This step is crucial as it transforms sulfur into a form that can be quantitatively measured.

4. **Precipitation of Barium Sulfate**: Once sulfuric acid is formed, it is then treated with an excess of barium chloride (BaCl₂). The barium ions react with the sulfate ions from the sulfuric acid to form barium sulfate (BaSO₄), which is a precipitate.

5. **Quantitative Measurement**: The barium sulfate precipitate can be filtered, dried, and weighed. The amount of barium sulfate formed is directly related to the amount of sulfur originally present in the sample. This allows for the quantitative estimation of sulfur.

6. **Conclusion**: Therefore, in the Carius method for the quantitative estimation of sulfur, sulfur is estimated by the formation of barium sulfate (BaSO₄) after oxidation to sulfuric acid.

### Answer:
In the Carius method for the quantitative estimation of sulfur, it is estimated by the formation of barium sulfate (BaSO₄).

---