A Radioactive Source Has a Half-Life of 2 Min $\times$ 10⁶
B)1

Multiple Choice

A radioactive source has a half-life of 2 min.At time t = 0 it is placed near a detector and the counting rate is observed to be 3000 counts/s.If the detection efficiency is 25%,how many radioactive nuclei are there at time t = 2 min?

A) 1.04 $\times$ 10⁶
B) 1.67 $\times$ 10⁶
C) 2.08 $\times$ 10⁶
D) 3.41 $\times$ 10⁶
E) 3.79 $\times$ 10⁶