How many aluminium atoms are there in the formula for aluminium nitrate ?

The formula for Aluminium Nitrate is .

This is because aluminium has a 3+ charge and nitrate has a 1- charge, so you need 3 of them to balance out aluminium.

Therefore, you have one ion of aluminium.

Where are the following questions

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.