Nuclear Physics And Radioactivity Question 326
Question: At any instant the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio of the substances [RPMT 1996]
Options:
A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 1 : 4
Show Answer
Answer:
Correct Answer: A
Solution:
Number of half lives in two days four substance 1 and 2 respectively are n1 = $ \frac{2\times 24}{12}=4 $ and $ n_{2}=\frac{2\times 24}{1.6}=3 $ By using $ N=N_{0}{{( \frac{1}{2} )}^{n}} $
Þ $ \frac{N_{1}}{N_{2}}=\frac{{{(N_{0})}{1}}}{{{(N{0})}{2}}}\times \frac{{{( \frac{1}{2} )}^{n{1}}}}{{{( \frac{1}{2} )}^{n_{2}}}} $ $ =\frac{2}{1}\times \frac{{{( \frac{1}{2} )}^{4}}}{{{( \frac{1}{2} )}^{3}}}=\frac{1}{1} $
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