Which of the following elements does not show allotropy?

Bismuth

The correct answer is option 2. Bismuth.

Allotropy refers to the existence of different forms of the same element in the same physical state. These different forms, known as allotropes, have distinct physical properties due to variations in atomic arrangement or bonding within the element.

Elements and Their Allotropes

1. Nitrogen (N₂):

Molecular Nitrogen (N₂): This is the most common form of nitrogen, consisting of diatomic molecules. It makes up about 78% of the Earth's atmosphere.

Solid Nitrogen: At extremely low temperatures, nitrogen can form solid allotropes with different structures, such as cubic nitrogen and hexagonal nitrogen.

2. Arsenic (As):

Grey Arsenic: The most stable allotrope at room temperature. It has a metallic appearance and a crystalline structure.

Yellow Arsenic: This form is less stable and exists as a molecular solid with a different arrangement of atoms compared to grey arsenic.

Black Arsenic: This form has a distinct structure and different physical properties compared to the other allotropes.

3. Antimony (Sb):

Grey Antimony: The stable allotrope at room temperature, with a metallic appearance and specific crystalline structure.

Yellow Antimony: Less stable and can be obtained under specific conditions. It has a different crystal structure from grey antimony.

4. Bismuth (Bi):

Bismuth does not exhibit allotropy. It exists in a single form under normal conditions. The element has a stable crystalline structure in its solid state and does not exhibit different forms with distinct physical properties.

Summary

Nitrogen, Arsenic, and Antimony all exhibit allotropy by existing in different structural forms that have distinct physical and chemical properties. Bismuth, on the other hand, does not show allotropy and exists as a single form with a specific crystalline structure.

This lack of allotropy in Bismuth means it does not have multiple distinct structural forms like the other elements listed.