The "diameter" of an n2 molecule is roughly 360 pm. how far (in μm) does one molecule in a sample of pure n2 typically travel before colliding with another n2 molecule, if the gas is held at stp.

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.