Which of the following elements does not show allotropy ?

Options

A. 1. Nitrogen
B. 2. Bismuth
C. 3. Antimony
D. 4. Arsenic

Answer

To determine which of the following elements does not show allotropy, we need to analyze the given options: nitrogen, bismuth, antimony, and arsenic.

### Step-by-Step Solution:

1. **Understanding Allotropy**:
- Allotropy refers to the existence of an element in more than one form, where the different forms (allotropes) have the same chemical formula but different physical properties.

2. **Identifying Elements**:
- The elements provided are nitrogen (N), bismuth (Bi), antimony (Sb), and arsenic (As).

3. **Analyzing Each Element for Allotropy**:
- **Nitrogen (N)**:
- Nitrogen primarily exists as a diatomic molecule (N₂) and does not exhibit allotropy in the same way as carbon does. The weak N-N bond limits its ability to form different structural forms.
- **Bismuth (Bi)**:
- Bismuth is known to have a stable form and does not exhibit variable oxidation states like other elements in its group. Therefore, it does not show allotropy.
- **Antimony (Sb)**:
- Antimony does exhibit allotropy; it has several allotropes, including yellow and black forms.
- **Arsenic (As)**:
- Arsenic also shows allotropy, with different forms such as gray, yellow, and black arsenic.

4. **Conclusion**:
- From the analysis, both nitrogen and bismuth do not show allotropy. However, since the question asks for elements that do not show allotropy, the answer includes both nitrogen and bismuth.

### Final Answer:
**Nitrogen and Bismuth do not show allotropy.**