Question: how many moles of molecules are there in 16g oxygen?
Answer: Here, we are given with 16 g of oxygen. The number of molecules in 16 gm of oxygen are 0.5 (= 16/32 moles). Thus the number of molecules in 16 gm or 0.5 mole of oxygen gas are 0.5 x 6.023 x 10^(23) = 3.012 x 10^(23) molecules.