A sample of sodium thiosulfate, Na2S2O3, weighing 38.1 mg contains radioactive sulfur-35 (with mass 35.0 amu). If

Question:

A sample of sodium thiosulfate, Na2S2O3, weighing 38.1 mg contains radioactive sulfur-35 (with mass 35.0 amu). If 22.3% of the sulfur atoms in the compound is sulfur-35 (the remainder is naturally occurring sulfur), how many disintegrations of this nucleus occur per second in this sample? Sulfur-35 has a half-life of 87.9 d.