Question

Why N2 exist as gas at room temperature but P4 is a solid ?

Answer 1

both the elements belong to the fifth group of the periodic table,atomic number of nitrogen is 7 and phosphorus is 15. Nitrogen is in second period and phosphorus in third of Mendeleev's periodic table. as one moves from top to bottom in a group the atomic radii increases nad as nitrogen is diatomic ,two atoms to form a molecule and phosphorus tetra atomic , the later becomes a solid because of lesser space available in between the molecules as compared to nitrogen.