Which of the following statements is true for `HNO_(2)`?

Options

A. It can be prepared by acidifying an aqueous solution of nitrite.
B. It is unstable weak acid which is known only in aqueous solution.
C. `N_(2)O_(3)` is an anhydride of `HNO_(2)`.
D. All of these

Explanation

To determine which of the statements about HNO₂ (nitrous acid) is true, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** HNO₂ can be prepared by acidifying an aqueous solution of nitrite.

**Analysis:**
- Nitrous acid (HNO₂) can indeed be prepared by adding a strong acid (like HCl) to a solution containing nitrite ions (NO₂⁻).
- For example, if we take sodium nitrite (NaNO₂) and treat it with cold dilute hydrochloric acid (HCl), we can produce HNO₂ and sodium chloride (NaCl).

**Equation:**
\[ \text{NaNO}_2 + \text{HCl} \rightarrow \text{HNO}_2 + \text{NaCl} \]

**Conclusion:** The first statement is true.

### Step 2: Analyze the second statement
**Statement:** HNO₂ is an unstable weak acid which is known only in aqueous solution.

**Analysis:**
- HNO₂ is indeed a weak acid and is considered unstable. It does not exist in a pure form and is typically found in aqueous solutions.
- When dissolved in water, it partially dissociates to form hydronium ions (H₃O⁺) and nitrite ions (NO₂⁻). However, the nitrite ion is not very stable due to charge dispersion.

**Conclusion:** The second statement is also true.

### Step 3: Analyze the third statement
**Statement:** N₂O₃ is an anhydride of HNO₂.

**Analysis:**
- An anhydride is a compound that can form an acid when reacted with water.
- When N₂O₃ (dinitrogen trioxide) is reacted with water, it produces HNO₂:

**Equation:**
\[ \text{N}_2\text{O}_3 + \text{H}_2\text{O} \rightarrow 2 \text{HNO}_2 \]

- This indicates that N₂O₃ can be considered an anhydride of HNO₂.

**Conclusion:** The third statement is true.

### Final Conclusion
Since all three statements about HNO₂ are true, the correct answer is that all of the statements are true.

### Summary of the Correct Option
- **Correct Option:** All of these statements are true.

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