Which one among the following does not have an allotrope ?

Options

A. Oxygen
B. Sulphur
C. Nitrogen
D. Carbon

Explanation

To determine which element does not have an allotrope, we can follow these steps:

### Step 1: Understand the Concept of Allotropes
Allotropes are different forms of the same element that exist in the same physical state. For example, carbon can exist as diamond and graphite, which are both solid forms of carbon.

### Step 2: Identify Elements with Known Allotropes
- **Carbon**: Has several allotropes including diamond, graphite, and fullerenes.
- **Oxygen**: Exists as O2 (dioxygen) and O3 (ozone).
- **Sulfur**: Has allotropes such as rhombic sulfur and monoclinic sulfur.

### Step 3: Analyze Nitrogen
- **Nitrogen**: The most common form is N2 (molecular nitrogen). While there are theoretical allotropes like N3 and N4, they are highly unstable and do not exist under normal conditions.

### Step 4: Conclusion
Among the elements mentioned, nitrogen does not have stable allotropes. Therefore, the answer to the question is nitrogen.

### Final Answer
**Nitrogen does not have an allotrope.**

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