Obtain the amount of 6027Co necessary to provide a radioactive source of 8.0 mCi strength. The half-life of 6027Co is 5.3 years.


The Strength a radioactive element is given by =

And, 1Ci = 3.7 × 1010decays/sec;


hence, 8.0 mCi = 8 × 10-3 × 3.7 × 1010


= 29.6 × 107 decay/sec ( 1 Ci = 3.7 × 1010 decay/sec)


Half life of Co60 is 5.3 years


= 5.3 × 365 × 86400 sec ( 1day = 86400 sec)


= 1.67 × 108 s-1


We know,


N = =


Mass of 7.133 × 1016 atoms will be = gms


Hence, we need gms of Co60.


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