The half life of radioactive sample undergoing α -decay is 1 . 4 × 10 17   s . If the number of nuclei in the sample is 2 . 0 × 10 21 , the activity of the sample is nearly:

Step-by-step solution

Recall the formula of activity of a radioactive element in terms of decay constat, R = λ N , and we know that the relation between decay constant and half-life is, T = 0 . 693 λ ⇒ R = 0 . 693 T × N ⇒ R = 0 . 693 1 . 4 × 10 17 × 2 × 10 21 ⇒ R = 10 4   Bq .