Technetium - 99 (43 99 ) has an excited state that decays by emission of a gamma ray. The half-life of the excited state is 360 min. What is the activity, in Curies (Ci) and in Becquerel (Bq), of 6.081x1024 atoms of this excited isotope ?

(2)A sample of radioactive materials decays so that the source is reduced from 1.5 curies to 0.25 curies in 60 days. Calculate the half-life of the substance.