How many oxygen atoms are in 1.60 g of quartz? hints?

Quartz has the formula SiO2
From the periodic table:
mass of oxygen = 16 grams
mass of silicon = 28.0855 grams
Mass of one mole of quarts = 28.0855 + 2(16) = 60.0855 grams

number of moles = mass / molar mass
number of moles = 1.6 / 60.0855 = 0.0266 moles

Each mole of quartz contains Avogadro's number of atoms.
Therefore:
number of atoms in 1.6 g = 1.6 x 6.02 x 10^23 = 1.603 x 10^22 atoms

Hi; /c