Which of the following are Pseudo halid

Options

A. `CN^-`
B. `N_3^-`
C. `OCN^-`
D. `Br^-`

Answer

To determine which of the given ions are pseudohalides, we need to understand the definition and characteristics of pseudohalides.

### Step-by-Step Solution:

1. **Understanding Pseudohalides**:
- Pseudohalides are anions that have properties similar to halogens. They are polyatomic ions that resemble halides (like fluoride, chloride, bromide, and iodide) in their chemical behavior.

2. **Identifying the Given Ions**:
- The ions provided in the question are:
- \( \text{CN}^- \) (Cyanide)
- \( \text{N}_3^- \) (Azide)
- \( \text{OCN}^- \) (Cyanate)
- \( \text{Br}^- \) (Bromide)

3. **Analyzing Each Ion**:
- **Cyanide (\( \text{CN}^- \))**:
- This ion consists of carbon and nitrogen. It has properties similar to halides and is classified as a pseudohalide.
- **Azide (\( \text{N}_3^- \))**:
- This ion contains three nitrogen atoms. It behaves like a halide and is also classified as a pseudohalide.
- **Cyanate (\( \text{OCN}^- \))**:
- This ion contains oxygen, carbon, and nitrogen. It also exhibits properties similar to halides, thus it is a pseudohalide.
- **Bromide (\( \text{Br}^- \))**:
- This is a true halide and does not qualify as a pseudohalide.

4. **Conclusion**:
- The ions that are classified as pseudohalides among the given options are:
- \( \text{CN}^- \) (Cyanide)
- \( \text{N}_3^- \) (Azide)
- \( \text{OCN}^- \) (Cyanate)
- Therefore, the correct answer includes options A, B, and C.

### Final Answer:
- The pseudohalides among the given options are \( \text{CN}^- \), \( \text{N}_3^- \), and \( \text{OCN}^- \).

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