question_answer

A radioactive nuclei with decay constant 0.5/s is being produced at a constant rate of 100 nuclei/s. If at t = 0 there were no nuclei, the time when there are 50 nuclei is:   [JEE ONLINE 11-04-2014]

A) 1s

B)

C)

D)

Correct Answer: B

Solution :

[b] Let N be the number of nuclei at any time t then,or

As, N = 50 and

Solving we get,