Why is it importana to have variables and untis included in a data table?

Because if they aren't properly included, it means that you are saying that the numbers can be anything, all reals.

Not including units is the same thing, if you don't properly lable the data table, you could be talking about anything.

Not giving a proper unit/variable is almost like giving someone permission to assume what you're talking about

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.

Answer two atoms of oxygen;