Nitrogen exist diatomic molecule and phosphorus as `P_(4).` Why ?

Explanation

Due to its small size and high electronegativity, nitrogen atom forms `ppi-ppi` multiple bonds with itself (triple bond), so it exists as a discrete diatomic molecule in elemental form, But phosphorus atom has large size and less electronegativity, so it as forms single bond instead of `ppi-ppi` multiple bond. Therefore, phosphorus exists as `P_(4)` molecule in its elemental form.