Question

A radioactive isotope has an activity of 9.98×104 Bq initially. After 3.00 hours the activity is 6.19×104 Bq. What is the half-life of the isotope?

What is the activity after an additional 3.00 hours?

Answer 1

Activity of a radioactive isotope after time t is given by
  

  
Now putting the given values,
   
we get the half life of the radioactive isotope as
  
  
So, the activity after additional 3 hrs, i.e., after time t = (3.00+3.00) hrs = 6.00 hrs, the activity is