Nitrogen and oxygen exist as diatomic but their congeners are `P_(4)` and `S_(8)` respectively because `:`

Options

A. phosphorus and sulphur are solids.
B. phosphorus and sulphur catenate due to the existance of `d-` orbitals and from strainless structures.
C. phosphorus and sulphur polymerise as soon as they are formed
D. catenation tendency of P and S is stronger because of the high `P-P` and `S-S` bond energies as compared to `N-N` and `O-O` bond energies

Explanation

To answer the question about why nitrogen and oxygen exist as diatomic molecules while their congeners exist as P₄ and S₈ respectively, we can analyze the properties of these elements and their bonding characteristics.

### Step-by-Step Solution:

1. **Understanding Diatomic Molecules**:
- Nitrogen (N₂) and oxygen (O₂) are diatomic molecules, meaning they consist of two atoms. This is due to their ability to form stable bonds with themselves.

2. **Examining Congeners**:
- The congeners of nitrogen and oxygen are phosphorus (P) and sulfur (S). Phosphorus exists as P₄ (tetraphosphorus) and sulfur as S₈ (octasulfur).

3. **Bonding in Nitrogen and Oxygen**:
- Nitrogen forms a triple bond (N≡N) in N₂, which is very strong and stable. Oxygen forms a double bond (O=O) in O₂, which is also stable. The strong bonding leads to their existence as diatomic molecules.

4. **Bonding in Phosphorus and Sulfur**:
- Phosphorus (P₄) forms a tetrahedral structure where each phosphorus atom is bonded to three others, creating a stable molecule with a lower bond order compared to nitrogen. This allows for a stable P₄ structure rather than existing as diatomic molecules.
- Sulfur (S₈) forms a crown-like structure with eight sulfur atoms, which allows for multiple single bonds between the atoms. The larger atomic size and lower electronegativity compared to oxygen lead to the formation of S₈ rather than diatomic sulfur (S₂).

5. **Conclusion**:
- The difference in bonding and molecular structure between nitrogen and phosphorus, and oxygen and sulfur, explains why nitrogen and oxygen exist as diatomic molecules while their congeners exist as P₄ and S₈. The stronger bonds in N₂ and O₂ favor their diatomic nature, while the larger atomic sizes and different bonding preferences in P and S lead to their polyatomic forms.

### Summary:
Nitrogen and oxygen exist as diatomic molecules due to strong triple and double bonds respectively, while phosphorus and sulfur exist as P₄ and S₈ due to their ability to form stable multi-atomic structures with lower bond orders.