The half-life of ¹⁹O is 29 s. Suppose that a scientist wishes to incorporate ¹⁹O into a molecule and then use its radioactivity to trace the fate of that molecule in a reaction. To make an accurate measurement, there must be at least 1.50 mg of ¹⁹O left by the end of the study, which will take 2.5 min each time the experiment is run. What is the minimum mass of ¹⁹O that must be used each time the experiment is conducted?