Define cell and atom bored​

Inot sure what it is i sorry : ((

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

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.