Positron emission tomography , carbon atom

In 2002, researchers at the Brookhaven National Laboratory in Upton, New York, examined brain samples from living baboons and mice that were administered toluene, a chemical found in many inhalants that is known to have abuse potential. By radiolabeling carbon atoms in toluene, the researchers mapped out the distribution of toluene in the brain and body using a technique called positron emission tomography (PET). 

All the stable isotopes of boron, carbon, nitrogen, oxygen, and fluorine are shown in the chart in the right hand column (in red), along with their radioactive isotopes with ti/2 > 1 min (in blue), (a) Write the chemical symbols, including mass and atomic numbers, for all of the stable isotopes, (b) Which radioactive isotopes are most likely to decay by beta emission (c) Some of the isotopes shown are used in positron emission tomography. Which ones would you expect to be most useful for this application (d) Which isotope would decay to 12.5%... 

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