Carbon and hydrogen are estimated by

Options

A. Liebig's method
B. Carius method
C. Duma's method
D. none of these.

Explanation

To solve the question "Carbon and hydrogen are estimated by," we will analyze the methods provided in the options and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding the Methods**:
- **Leibig's Method**: This method involves the combustion of an organic compound in the presence of oxygen. The carbon in the compound is oxidized to carbon dioxide (CO2), and the hydrogen is oxidized to water (H2O). The amounts of CO2 and H2O produced are used to calculate the percentages of carbon and hydrogen in the original compound.
- **Carius Method**: This method is primarily used for the quantitative analysis of halogens in organic compounds, not for carbon and hydrogen.
- **Dumas Method**: This method is used for the estimation of nitrogen in organic compounds, not for carbon and hydrogen.

2. **Analyzing the Options**:
- **Option 1: Leibig's Method** - This is the correct method for estimating carbon and hydrogen.
- **Option 2: Carius Method** - Incorrect, as it is used for halogen analysis.
- **Option 3: Dumas Method** - Incorrect, as it is used for nitrogen estimation.
- **Option C: None of these** - Incorrect, since Leibig's method is a valid option.

3. **Conclusion**:
- The correct answer is **Option 1: Leibig's Method**.

### Final Answer:
Carbon and hydrogen are estimated by **Leibig's method**.