which of the following is the anhydride of `NHO_2` ?

Options

A. `N_2O`
B. `N_2O_3`
C. `N_2O_4`
D. `NO`

Answer

To determine the anhydride of nitrous acid (NHO₂), we need to understand the concept of acid anhydrides and their relationship with the corresponding acids.

### Step-by-Step Solution:

1. **Understanding Anhydrides**: An anhydride is a compound that can react with water to form an acid. For example, if we have an acid (like H₂SO₄), its anhydride would be SO₃.

2. **Identifying the Acid**: In this case, the acid we are dealing with is nitrous acid (NHO₂).

3. **Finding the Anhydride**: To find the anhydride of nitrous acid, we look for a nitrogen oxide that can react with water to produce NHO₂.

4. **Known Anhydrides**:
- Dinitrogen trioxide (N₂O₃) is known to be the anhydride of nitrous acid.
- Dinitrogen pentoxide (N₂O₅) is the anhydride of nitric acid (HNO₃).

5. **Conclusion**: Therefore, the anhydride of NHO₂ is N₂O₃.

### Final Answer:
The anhydride of NHO₂ is **dinitrogen trioxide (N₂O₃)**.

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