Science has some limitations: It can be used only to answer certain types of questions. Which of the following questions can be answered using a scientific
approach? (Check all that apply.)

The number of protons in a nucleus

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.