Let’s clarify what we’re talking about. In nature there are two atoms of oxygen in each molecule.
Your sample of oxygen would contain (6.02 * 10^23 ) * 2.648 = 15.94 * 10^23 molecules of oxygen.
There would be 31.88 * 10^23 atoms of oxygen.
In standard form the answer is 3.19 * 10^24 atoms of oxygen in your sample.
hope it helps (ー_ー゛)
