The atomic mass of silicon is 28 g/mol. Therefore, 521 mg or 0.521 g will be equivalent to; 0.521/28 = 0.01861 mooles Atomic mass of cobalt is 27 g/mol According to Avogadro's law the mass of cobalt that will have the same atom as 52 mg of silicon will be ; (0.01861 moles × 27) = 0.5024 g or 502.4 mg
