A sample of nitrogen gas is collected in a 2.00 L bottle by water displacement. The total pressure exerted by the “wet” nitrogen gas in the bottle is 755.0 mm Hg. If the temperature of the system is 20.0 ºC, what is the pressure exerted by the “dry” nitrogen gas?

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.