PHYSICAL SCIENCE
'(<a href="http://www.j-archive.com/media/2006-05-31_DJ_08.jpg" target="_blank">Jon of the Clue Crew explains the diagrams on the monitor.</a>)  For 5 out of 10 carbon-11 atoms to decay into boron-11, it takes 20 minutes, which is this measure for the carbon-11 isotope'
the half-life