Question

What is the probability of a radioactive nucleus to survive one mean life?
A. (a) `1/e`
B. (b) `(1)/(e+1)`
C. (c) `1-1/e`
D. (d) `1/e-1`

Answer 1

Correct Answer - A
Probability of survival,
P=Number of nuclei left/Initial number of nuclei`=(N_0e^(-lambdat))/(N_0)`
At `t=`one mean life`=1/lambda`
`P=e^-1=1/e`