Question

A compound contains 14.5 g of magnesium and 3.5 g of oxygen. What is the mass percent of oxygen in the compound?

Answer 1

80.5%- The total mass of the compound is 18g (14.5 + 3.5) then divide the mass of magnesium by the total. easy way to remember is- (part/whole) x 100

Answer 2

im not completely sure if this is correct, but this is what I did. and how I got my answer.

(3.5 g) / (14.5 + 3.5) g = 0.19 = 19% O by mass