A radioactive isotope has a lifetime of 6.30 min.If you begin with a sample of this isotope and there are 2.05 * 10²¹ atoms left after one hour,how many moles were in your initial sample?

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The half-life of the isotope is 6.30 minutes, so in one hour (60 minutes), approximately 9.52 half-lives have passed. The number of atoms remaining after one hour is 2.05 * 10^21. Using the decay formula, calculate the initial number of atoms and convert to moles using Avogadro's number (6.022 * 10^23 atoms/mole).

A Radioactive Isotope Has a Lifetime of 6