The half-life for the radioactive decay of Ce−141 is 32.5 days. If a sample has an activity of 4.0 μCi after 130 d have elapsed, what was the initial activity, in microcuries, of the sample? Express your answer using two significant figures.

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.