The given compound is ZnCO3
So each mole of ZnCO3 will have three moles of Oxygen atoms
So if the number of oxygen atoms in the sample = 3.11×10^22
It means the moles of oxygen atoms = number of atoms / Na (avagadro's number)
moles of oxygen atoms = 3.11×10^22 / 6.023 X 10^23 = 0.0516 moles
Mass of oxygen atoms = moles X atomic mass = 0.0516 X 16 = 0.8256 g
