The question is wrong
The question is full wrong but how can I answer the question
from the mass of ra 226, one can determine the number of atoms. then one may use the definition of activity, is: a = λn, where λ is the decay constant, and n is the number of atoms. λ can be determined from the half-life, if it is not already know. a can be written in decays, or disintegrations per sec, dps, and one should know the value of ci in dps.