In Dumas method for the estimation of `N_(2)`,the sample is heated with copper oxide and the gas evolved is passed over :

Options

A. Copper gauze
B. `Pd`
C. `Ni`
D. Copper oxide

Answer

To solve the question regarding the Dumas method for the estimation of nitrogen, let's break down the steps involved in the process:

### Step-by-Step Solution:

1. **Understanding the Dumas Method**:
The Dumas method is a classical technique used for the determination of nitrogen content in organic compounds. The principle behind this method is that nitrogen in the organic sample is converted to nitrogen gas (N₂) upon combustion.

2. **Heating with Copper Oxide**:
In this method, the organic sample is heated in the presence of copper oxide (CuO). The copper oxide acts as an oxidizing agent that facilitates the combustion of the organic sample, converting nitrogen present in the sample into nitrogen gas.

3. **Gas Evolution**:
During the heating process, nitrogen gas (N₂) is evolved along with other gases. The nitrogen gas is what we are interested in measuring.

4. **Passing the Evolved Gas**:
The evolved gas, which contains nitrogen, is then passed over a substance that can absorb or react with any other gases present, ensuring that we only measure the nitrogen gas.

5. **Final Step - Identifying the Absorbent**:
According to the Dumas method, the evolved gas is typically passed over copper gauze. The copper gauze helps in the removal of any excess oxygen or other gases, allowing for the accurate estimation of nitrogen.

### Conclusion:
Thus, the correct answer to the question is that in the Dumas method for the estimation of nitrogen, the gas evolved is passed over **copper gauze**.