Nuclear Physics And Radioactivity Question 121
Question: In a mean life of a radioactive sample
Options:
A) About 1/3 of substance disintegrates.
B) About 2/3 of the substance disintegrates
C) About 90% of the substance disintegrates
D) Almost all the substance disintegrates
Show Answer
Answer:
Correct Answer: B
Solution:
[b] By using $ N=N_{0}{{e}^{-\lambda t}} $ and $ t=\tau =\frac{1}{\lambda } $ Substance remains $ N=\frac{N_{0}}{e}=0.37N_{0}\simeq \frac{N_{0}}{3} $
$ \therefore $ Substance disintegrated $ =N_{0}-\frac{N_{0}}{3}=\frac{2N_{0}}{3} $
BETA
