Question

A radioactive material, having a mean life of 10⁹ s, has an activity of 10¹⁰ disintegrations per second, at a given instant. If the mass of one atom of this material is 10^–25 kg, the total mass (in mg) of this material, present at the given instant, is 

(1) One 

(2) Half 

(3) Two 

(4) One and a half

Answer 1

Correct option : (1) One

Explanation :

Let N be the number of radioactive nuclei present in the sample, at the given instant and let λ be its disintegration constant. Then