Nuclear Physics And Radioactivity Question 83
Question: A radioactive sample is a-emitter with half life 138.6 days is observed by a student to have 2000 disintegration/sec. The number of radioactive nuclei for given activity are
Options:
A) 3.45 ´ 1010
B) 1 ´ 1010
C) 3.45 ´ 1015
D) 2.75 ´ 1011
Show Answer
Answer:
Correct Answer: A
Solution:
Activity of substance that has 2000 disintegration/sec $ =\frac{2000}{3.7\times 10^{10}}=0.054\times {{10}^{-6}}ci=0.054,\mu ci $ The number of radioactive nuclei having activity A $ N=\frac{A}{\lambda }=\frac{2000\times {T_{1/2}}}{{\log_{e}}2} $ $ =\frac{2000\times 138.6\times 24\times 3600}{0.693}=3.45\times 10^{10} $
BETA
