posted by Casey .
If a mineral sample has a mass of 10 g, how many grams of oxygen does it contain?
You need more information than that to determine the amount of oxygen or any other element in the mineral. Your question is the same kind as, "My car was in the rain today. How much did it rain?"
you need more info!
Sorry, there is 40% oxygen.
If the compound has 40% oxygen, that means there are 40g oxygen in 100 g sample. So how many g oxygen will be in a 10g sample?