Question

A mixture of the compounds sodium oxide and magnesium chloride contains 2.4182 g of sodium oxide and is 89.3 % by mass magnesium chloride. The sodium oxide is 74.200 % by mass sodium. Calculate the moles of oxygen in the mixture.

Thanks in advance.

Answer 1

All of those numbers are meant to confuse you. You need only grams Na2O. The other numbers are useless.
2.4182 g Na2O/molar mass = mols Na2O
mols O = mols Na2O.

Answer 2

I knew something was fishy about this question. Thank you!