Question

For a given sample, the counting rate is 47.5 α particle/min. After 5 minutes the count is reduced to 27 α particles/min. Then the half life of the sample is 

(1) 11 minute 

(2) 5.99 minute 

(3) 0.59 minute

(4) 0.11 minute

Answer 1

Correct option : (2) 5.99 minute

Explanation:

Initial counting rate = 47.5 a particles/min 

Final counting rate after 5 minutes 27α particles/min