Which pseudo-halogen does not have dimeric nature

Options

A. cyanogen
B. azide
C. thiogene
D. selenothiogene

Answer

To determine which pseudo-halogen does not have dimeric nature, we need to analyze the given options. Pseudo-halogens are compounds that exhibit similar properties to halogens but are not halogens themselves. Dimeric nature refers to the ability of a molecule to exist as a dimer, which means it can pair up with another molecule of the same kind.

### Step-by-Step Solution:

1. **Identify the Pseudo-Halogens**: The question provides four options:
- Sinogen (CN)
- Azide (N3^-)
- Thiogen (e.g., thiocyanate, SCN)
- Selenothiogen (e.g., SeCN)

2. **Analyze Sinogen (CN)**:
- Sinogen is known to exist in a dimeric form, specifically as C2N2 (or CN)2.
- Therefore, Sinogen has dimeric nature.

3. **Analyze Azide (N3^-)**:
- Azide is a simple ion with the formula N3^-.
- It does not exist in a dimeric form; it is a monomeric species.
- Thus, Azide does not have dimeric nature.

4. **Analyze Thiogen**:
- Thiogen refers to a class of pseudo-halogens, and one example is thiocyanate (SCN).
- Thiocyanate can exist in a dimeric form as (SCN)2.
- Therefore, Thiogen has dimeric nature.

5. **Analyze Selenothiogen**:
- Selenothiogen (e.g., SeCN) can also exist in a dimeric form.
- Thus, Selenothiogen has dimeric nature.

6. **Conclusion**:
- Among the options analyzed, only Azide (N3^-) does not have dimeric nature.
- Therefore, the answer to the question is **Azide**.

### Final Answer:
The pseudo-halogen that does not have dimeric nature is **Azide (N3^-)**.