Nuclear Physics And Radioactivity Question 20
Question: Assertion : Radioactivity of $ 10^{8} $ undecayed radioactive nuclei of half-life of 50 days is equal to that of $ 1.2\times 10^{8} $ number of undecayed nuclei of some other material with half-life of 60 days Reason : Radioactivity is proportional to half-life.
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: C
Solution:
Radioactivity $ =-\frac{dN}{dt}=\lambda N=\frac{0.693N}{T} $ $ =\frac{0.693\times 10^{8}}{50}=\frac{0.693\times 1.2\times 10^{8}}{60} $ $ =0.693\times 2\times 10^{6}. $ Radioactivity is proportional to 1/T1/2, and not to T1/2.
BETA
