1. Tritium (T) decays by emitting a low-energy particles. This radiation acts on a phosphor producing illumination.Illuminators can thus be made by adding tritium to a phosphor in the form of paint which are sealed in a plastic container that is transparent to illumination but that blocks the particles so that no hazard is encountered. The illuminators are used for such devices as locks, aircraft safety markers, exit signs, etc. Regulations limit the amount of original radioactivity in such devices, depending upon service. Assuming that 4 mci are permitted for an aircraft safety device, calculate (a)the maximum mass of tritium that can be used, in grams, and (b) the percent decrease in luminosity (which is proportional to radioactivity) after 10 years time.

[1 millicurie (mci) = 10^-3 ci (curie)