1.   Asteroids contain a variety of rare radioactive isotopes of potassium, uranium, thorium, rubidium, and so on.

2.   Every radioactive isotope provides an independent clock for measuring geological time.

3.   She could hear the adjacent streetlight sizzling like a radioactive isotope.

4.   The simplest radioactive methods are based on Decay of a radioactive isotope into a stable one.

5.   The time taken for half of the atoms of a radioactive isotope to Decay is called its half-life.

6.   ...tritium, a radioactive isotope of hydrogen.

7.   The second has been measured by studying the movements of barium, or radio-opaque shapes and more recently radioactive isotopes.

8.   Anti-nuclear activists warn that the tests could release a hard-to-control radioactive isotope, tritium, into the environment.

9.   Attaching a radioactive isotope to a monoclonal can enhance its ability to kill tumors.

10.   Australians have a penchant for making the names of some of their best wines sound like radioactive isotopes.