Question

Nitrogen from n2 but phosphorus as p4 at instant reason is

Answer 1

due to catenation power, electronegativty, high bond dissociation energy, small size, absence of d orbital of N2

Answer 2

Due to larger atomic size P is unable to form pi bonds and so it is tetra-atomic in which each P atom is linked with 3 other P atoms by 3 sigma bond.But, due to smaller atomic size N forms 1 sigma and 2 pi bonds i.e. triple bonds with other N atom and exists as diatomuc molecule.