Answer: 0.37g
Explanation:avogadro number = 6.02214076x10^23 atoms/molecules per mole
a mole of Na2O = 2*23 + 16 = 52 g
4.25x10^21 atoms = 52*(4.25*10^21/6.02214076*10^23) = 0.37 g
I believe it is d. scientific law
Iron (II) oxide is composed of iron with an oxidation number of +2 (shown by the II after iron) and an oxygen that has an oxidation number of -2 (oxygen almost always has an oxidation state of -2). Since the anion and cation both have a charge of +or- 2, they bond with each other with a 1 to 1 ratio and the formula should be FeO
I hope this helps. Let me know if anything is unclear.