An ion that has 18e- and a net charge of +2
Question 9 answers
has 16 protons.
has 18 neutrons.
is an anion.
has the symbol Ar2+.
has the same number of electrons as an argon atom.

A lot of this information doesn't make sense.

If it has 18 electrons and 2+, then it must have 20 protons, which doesn't make it Ar2+, it makes it Ca2+.
This also has 20 neutrons. But it does have the same number of electrons as an argon atom, and it is a cation because it has a positive charge.

Something is very wrong here :D