The ratio of radioactive parent to stable daughter atoms in a mineral is measured as 1:3.How many half-lives have elapsed since the mineral grain formed, assuming that only parent atoms were present when it crystallized?
A)2.0
B)0.5
C)3.0
D)1.5

Question

Quizplus · Accepted Answer

After one half-life, the ratio of parent to daughter atoms would be 1:1. After two half-lives, the parent atoms would have undergone another halving, leading to a ratio of 1:3 (1 part parent to 3 parts daughter), indicating that two half-lives have passed.

The Ratio of Radioactive Parent to Stable Daughter Atoms in a Mineral