A rock sample containing an isotope with a half-life of 28 million years has an initial mass of 184 grams. How much daughter isotope is present after three half-lives?
A) 23 grams
B) 46 grams
C) 69 grams
D) 115 grams
E) 161 grams

Question

Quizplus · Accepted Answer

After three half-lives, the original isotope will have reduced to 1/8 of its initial mass (184 grams), leaving 23 grams of the original isotope. The remaining mass (161 grams) will have transformed into the daughter isotope.

A Rock Sample Containing an Isotope with a Half-Life of 28