Which of the following is 'a' FALSE statement

Options

A. Carius tube is used in the estimation of sulphur in an organic compound
B. Carius method is used for the estimation of nitrogen in an organic compound
C. Phosphoric acid produced on oxidation of phosphorus present in an organic compound is precipitated as `Mg_2 P_2 O_7` by adding magnesia mixture.
D. Kjeldahl's method is used for the estimation of nitrogen in an organic compound

Answer

To determine which statement is false among the given options, we will analyze each statement one by one based on the information provided in the video transcript.

### Step-by-Step Solution:

1. **Analyze Statement 1: Zeldal Method for Nitrogen Estimation**
- The Zeldal method is indeed used for the quantitative determination of nitrogen in organic compounds. It is a well-established method in analytical chemistry.
- **Conclusion:** Statement 1 is true.

2. **Analyze Statement 2: Carious Method for Halogens and Sulfur**
- The Carious method is used for the determination of halogens in organic compounds. It involves heating the organic compound with nitric acid in the presence of silver nitrate, which helps in the formation of silver halides.
- Additionally, the Carious method can also be used for sulfur, but without the addition of silver nitrate.
- **Conclusion:** Statement 2 is true.

3. **Analyze Statement 3: Phosphorus Oxidation to H3PO4**
- The statement mentions that phosphorus in organic compounds is oxidized to phosphoric acid (H3PO4) and precipitated as magnesium pyrophosphate (Mg2P2O7) using a magnesia mixture.
- This process is accurate; phosphorus is oxidized by nitric acid to form H3PO4, and then it can be precipitated using a mixture of ammonium chloride and magnesium chloride.
- **Conclusion:** Statement 3 is true.

4. **Identify the False Statement**
- After analyzing all three statements, we find that:
- Statement 1 is true (Zeldal method for nitrogen).
- Statement 2 is true (Carious method for halogens and sulfur).
- Statement 3 is true (Phosphorus oxidation to H3PO4).
- Since all the statements analyzed are true, we conclude that the false statement must be related to the Carious method, which is incorrectly associated with nitrogen.

### Final Conclusion:
The false statement is **Statement 2**, as the Carious method is not used for nitrogen determination.