How can geologist test a mineral to determine its identity? a. compare its hardest to known minerals b. measure it’s mass c. make sure it is made up of only one element d. measure its volume

A. Compare its hardness to known minerals

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.