# Given the following chart, what will the rock contain after 40.000 years or 2 half-lives?

##### 1 Answer

Mar 5, 2017

#### Answer:

There is

#### Explanation:

After one half-life, the amount of unstable isotope halves. After another half-life, that amount halves again, so

The unstable product decays into the stable product and the total mass remains the same. Adding together the mass of unstable and stable isotopes, it is always