The statement true for `N_(3)^(-)` is

Options

A. It has a non-linear structure
B. It is called pseudo halogens
C. The formal oxidation state of `N` in this anion is-1
D. It is isoelectronic with `NO_(2)`

Explanation

To determine which statement is true for the azide ion \( N_3^- \), we can analyze the given options step by step.

### Step 1: Determine the Structure of \( N_3^- \)
The azide ion \( N_3^- \) consists of three nitrogen atoms. The arrangement of these nitrogen atoms can be analyzed using VSEPR theory.

- **Hint**: Consider the number of bonding pairs and lone pairs around the central atom to determine the molecular geometry.

**Conclusion**: The structure of \( N_3^- \) is linear, not non-linear.

### Step 2: Identify if \( N_3^- \) is a Pseudohalogen
Pseudohalogens are species that resemble halogens in their chemical behavior but are not true halogens.

- **Hint**: Compare the properties of \( N_3^- \) with those of halogens to see if they exhibit similar characteristics.

**Conclusion**: \( N_3^- \) is indeed referred to as a pseudohalogen because it shares some properties with halogens.

### Step 3: Calculate the Formal Charges on Nitrogen Atoms
To find the formal charges on each nitrogen atom in \( N_3^- \), we use the formula:
\[ \text{Formal Charge} = \text{Valence Electrons} - \left( \frac{\text{Bonding Electrons}}{2} \right) - \text{Non-bonding Electrons} \]

1. **First Nitrogen**:
- Valence Electrons: 5
- Bonding Electrons: 4 (2 bonds with adjacent nitrogens)
- Non-bonding Electrons: 4
- Calculation: \( 5 - \left( \frac{4}{2} \right) - 4 = 5 - 2 - 4 = -1 \)

2. **Second Nitrogen** (central nitrogen):
- Valence Electrons: 5
- Bonding Electrons: 8 (4 bonds total)
- Non-bonding Electrons: 0
- Calculation: \( 5 - \left( \frac{8}{2} \right) - 0 = 5 - 4 = +1 \)

3. **Third Nitrogen**:
- Valence Electrons: 5
- Bonding Electrons: 4 (2 bonds with adjacent nitrogens)
- Non-bonding Electrons: 4
- Calculation: \( 5 - \left( \frac{4}{2} \right) - 4 = 5 - 2 - 4 = -1 \)

- **Hint**: Remember to account for all bonding and non-bonding electrons when calculating formal charges.

**Conclusion**: The formal charges are -1 for the first nitrogen, +1 for the central nitrogen, and -1 for the third nitrogen, which adds up to the overall charge of -1 for \( N_3^- \).

### Step 4: Check if \( N_3^- \) is Isoelectronic with \( NO_2 \)
Isoelectronic species have the same number of total electrons.

- For \( N_3^- \):
- Total electrons: \( 3 \times 7 + 1 = 22 \) (3 nitrogen atoms, each with 7 valence electrons, plus 1 for the negative charge)

- For \( NO_2 \):
- Total electrons: \( 7 + 2 \times 8 = 23 \) (1 nitrogen with 7 valence electrons and 2 oxygens with 8 each)

- **Hint**: Count the total number of electrons carefully for each species to determine if they are isoelectronic.

**Conclusion**: \( N_3^- \) is not isoelectronic with \( NO_2 \) since they have different total electron counts (22 vs. 23).

### Final Conclusion
The only true statement for \( N_3^- \) is that it is called a pseudohalogen. The other statements regarding its structure, formal charge, and isoelectronic nature are incorrect.