`NO_(2)` can not be dried by an alkali, why ?

Answer

To understand why \( NO_2 \) cannot be dried by an alkali, we can break down the explanation into a few logical steps:

### Step-by-Step Solution:

1. **Identify the Nature of \( NO_2 \)**:
- \( NO_2 \) (Nitrogen dioxide) is classified as an acidic oxide. This means it can react with bases (alkalis).

2. **Identify the Alkali**:
- Consider a common alkali such as sodium hydroxide (\( NaOH \)). This is a strong base.

3. **Reaction Between \( NO_2 \) and Alkali**:
- When \( NO_2 \) reacts with \( NaOH \), a chemical reaction occurs:
\[ NO_2 + NaOH \rightarrow NaNO_2 + NaNO_3 + H_2O \]
- In this reaction, sodium nitrite (\( NaNO_2 \)), sodium nitrate (\( NaNO_3 \)), and water (\( H_2O \)) are formed.

4. **Formation of Water**:
- The key point here is that water is produced as a byproduct of the reaction. Since drying implies the removal of water, the formation of water means that \( NO_2 \) cannot be effectively dried using an alkali.

5. **Conclusion**:
- Therefore, \( NO_2 \) cannot be dried by an alkali because the reaction between \( NO_2 \) and the alkali results in the formation of water, which contradicts the purpose of drying.

### Summary:
The reason \( NO_2 \) cannot be dried by an alkali is due to the reaction between \( NO_2 \) and the alkali (like \( NaOH \)), which produces water as a byproduct. This water prevents the drying process.