if 5.2 grams of bismuth react under certain conditions with 10.0 g of oxygen what is the empirical formula of the bismuth formed
I don't like problems like this because it is obviously a "made-up" problem.
mols Bi = 5.2/208.98 = 0.02488
mols O2 = 10/32 = 0.625 or 1.25 mol O
Now find the ratio of Bi to O. The easy way to do that is divide the smaller number by itself, then divide the other number by the same small number. Round to whole numbers. I get something like BiO50.
Check my work carefully; perhaps I've made a mistake.