Question

If a mineral has a parent to daughter ratio of 1:3 (one parent atom for every three daughter atoms), how many half-lives have passed since the mineral formed?

a. 0
b. 1
c. 2
d. 3
e. 4

Answer 1

c. 2

Step-by-step explanation:

Given that

Parent to daughter ratio = 1:3

Based on the above information, after considering the 1 half-life of radioactive isotope there is one-half of the real radioactive atoms of the parent left also the equivalent number of daughter atoms produced

Therefore after one half, the ratio between parent and daughter atom is 1:1

Now after the second half, half of the left parent atom would be transformed into the daughter cells

This remains a quarter of parent atom and 3 quarter of daughter atoms

So, the ratio of 1:3 would be shown after 2 half-lives