Which gas is introduced intot the combustion tube in Liebig's method ?

Options

A. Pure and dry `CO_(2)`
B. Pure and dry `N_(2)`
C. Pure and dry `O_(2)`
D. Pure and dry He

Answer

### Step-by-Step Solution:

1. **Understanding Liebig's Method**: Liebig's method, also known as Liebig's combustion method, is used for the estimation of carbon and hydrogen in organic compounds.

2. **Setup of the Apparatus**: The method involves a combustion tube, which is a long glass tube. This tube is packed with substances like cuprous oxide (CuO) and copper gauze.

3. **Introduction of Gases**: The combustion tube has two ends. One end is connected to a U-tube containing anhydrous calcium chloride and a potash bottle with concentrated KOH, while the other end is used for introducing a gas.

4. **Gas Required for Combustion**: In Liebig's method, the gas that is introduced into the combustion tube is **pure and dry oxygen**. This oxygen is essential for the complete combustion of the organic compound present in the tube.

5. **Purpose of Oxygen**: The introduction of pure and dry oxygen allows for the combustion of the organic compound, resulting in the formation of carbon dioxide (CO2) and water (H2O). These products are then collected and weighed to determine the percentage of carbon and hydrogen in the original compound.

6. **Conclusion**: Therefore, the gas introduced into the combustion tube in Liebig's method is **pure and dry oxygen**.