What is the atomicity of Phosphorus?

Tetra-atomic

The correct answer is option 4. Tetra-atomic.

The atomicity of phosphorus depends on the allotrope of phosphorus in question. Phosphorus exhibits several allotropes, but the most common ones are white phosphorus, red phosphorus, and black phosphorus.

1. White Phosphorus (P₄): White phosphorus exists as P₄ molecules, and each molecule contains four phosphorus atoms. So, the atomicity of white phosphorus is tetra-atomic.

2. Red Phosphorus: Red phosphorus has a polymeric structure and does not exist as discrete P₄ molecules. It consists of a network of phosphorus atoms. Therefore, the atomicity of red phosphorus is polyatomic.

3. Black Phosphorus:  Black phosphorus is composed of puckered sheets of phosphorus atoms. The structure is different from white and red phosphorus, and it can be considered poly-atomic or polymeric.

Considering the common allotropes, the most straightforward answer is tetra-atomic for white phosphorus. However, it's essential to note that phosphorus can exhibit different structures with varying atomicities.