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Quartz is SiO?. So the molecular mass is 28.0855 + 2(15.9994) = 60.084 g/mol. 1.90 g / 60.084 g/mol = 0.0316 mol. In each mole of quartz, there are 2 Oxygen atoms, so that means 0.063 mol of oxygen.
SiO2 also known as quartz or silica. 6.02 × 10^23 avagadros #. so now this is a very straight forward question. ( 1.03 g SiO2 ) * (1mol SiO2/60.1g)(2 mol O2/1 mol SiO2) ( 6.02*10^23 atoms / 1 mol o2) = 2.063054 × 10^22 atoms
