Which of the following is not polyatomic ?

Options

A. Nitrogen
B. Sulphur
C. Ozone
D. Phosphorus

Explanation

To determine which of the following substances is not polyatomic, we need to understand the definition of polyatomic and analyze each option provided.

### Step-by-Step Solution:

1. **Understand Polyatomic**:
- Polyatomic refers to a molecule that consists of more than two atoms. The term "poly" means many, and "atomicity" refers to the number of atoms in a molecule.

2. **Analyze Each Option**:
- **Option 1: Nitrogen (N2)**
- Nitrogen exists as a diatomic molecule (N2), which means it has only 2 atoms. Therefore, nitrogen is not polyatomic.
- **Option 2: Sulfur (S8)**
- Sulfur exists as S8 at room temperature, which means it has 8 atoms. This qualifies as polyatomic.
- **Option 3: Ozone (O3)**
- Ozone consists of 3 oxygen atoms (O3), which also qualifies as polyatomic.
- **Option 4: Phosphorus (P4)**
- Phosphorus typically exists as P4, indicating it has 4 atoms. This is also polyatomic.

3. **Conclusion**:
- After analyzing all the options, we find that the only substance that is not polyatomic is **Option 1: Nitrogen (N2)**.

### Final Answer:
The substance that is not polyatomic is **Nitrogen (N2)**.

---