Kjeldahl's method is used in the estimation of

Options

A. (a) nitrogen
B. (b) halogens
C. (c) sulphur
D. (d) oxygen

Explanation

**Step-by-Step Solution:**

1. **Understanding Kjeldahl's Method**:
- Kjeldahl's method is primarily a technique used in chemistry to determine the nitrogen content in various substances.

2. **Application of the Method**:
- This method is applicable to both organic and inorganic compounds. In organic compounds, it helps quantify the nitrogen present, while in inorganic compounds, it can be used to measure nitrogen in forms such as ammonia (NH3) and ammonium ions (NH4+).

3. **Limitations of the Method**:
- It is important to note that Kjeldahl's method is not suitable for estimating nitrogen in all inorganic compounds. It specifically measures nitrogen in organic compounds and certain inorganic forms (like ammonia).

4. **Evaluating the Options**:
- The question provides four options:
- A) Nitrogen
- B) Halogens
- C) Sulphur
- D) Oxygen
- Based on the understanding of Kjeldahl's method, we can conclude that it is specifically used for the estimation of nitrogen.

5. **Conclusion**:
- Therefore, the correct answer to the question "Kjeldahl's method is used in the estimation of" is **Option A: Nitrogen**.

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