I have problem with doing this, and only thing I can see is this particle is ion 2-!
How to think in this kind of exercises!
OK, you are correct - this is an ion with a charge of 2-
Now, out of 32 electrons, 24 are valence electrons (outer shell) - so where are the other 8? They must be in the inner shells...
If we have an ion that has 8 inner shell electrons in total, made up of four atoms, what might that tell you about which period these atoms must come from?
Hint: Think about how many inner shell (non-valence) electrons do the atoms from each period have, and remember there are four atoms in the unknown ion...