How many moles of gold atoms are in 2.8 x 10 21 atoms of gold?

Disregard the previous answer. You are not given anything in the way of grams, so you cannot assume the number of g from this. You would use Avogadro's Number, 6.02x10^23 in this case. I've attached a picture of how I found it. (Ignore my Statistics notes lol)

I didn't see any statements, but here are some similarities of those elements:

They all have the same number of valence electrons, they will become cations, they all will lose 2 electrons, they will behave similarly in chemical reactions, they have similar chemical properties, they all are in the alkaline earth metal family. Hope this helps! :)