What is 5.06 grams of oxygen in atoms

Convert grams to mols and then mols to atoms using Avogadro’s number (6.02 x 10^23).

5.06 g O2 / 32 g O2 x (6.02 x 10^23)

Number of moles=mass of oxygen/ molar mass of oxygen=5.06/16=0.38mol
number of atoms of oxygen=number of moles of oxygen x Avogadro's number=0.38x6.022x10 to the power 23=2.29x10 to the power 23 atoms