The diagram below shows the radioactive decay of cesium (135Cs). ...

[rl]

The diagram below shows the radioactive decay of cesium (¹³⁵Cs). What is the half-life of ¹³⁵Cs?
 
 

Question 2

The diagram below illustrates the radioactive decay of Potassium (⁴⁰K), which has a half-life of 1.3 billion years. If a lunar rock is found that currently contains 5 grams of ⁴⁰K, and it is determined that the sample contained 20 grams when it was formed, how old is the lunar rock?
 
 
   
  a.
  6.5 billion years
  b.
  19.5 billion years
  c.
  2.6 billion years
  d.
  3.9 billion years
  e.
  4.6 billion years

[blazinlyss]

Answer to Question 1

3 million years

Answer to Question 2

C

[rl]

Thanks for the timely response, appreciate it

[mammy1697]

Wow, this really help