Nuclear Chemistry Question 25

Question: A radioactive nucleide X decays at the rate of $ 1.00\times 10^{5} $ disintegration $ {{s}^{-1}}{{g}^{-1}} $ . Radium decays at the rate of $ 3.70\times 10^{10} $ disintegration $ {{s}^{-1}}{{g}^{-1}} $ . The activity of X in millicuries $ {{g}^{-1}} $ $ (mci{{g}^{-1}}) $ is

[MP PET 2001]

Options:

A) 0.027

B) $ 0.270\times {{10}^{-5}} $

C) 0.00270

D) 0.000270

Show Answer

Answer:

Correct Answer: B

Solution:

$ \frac{dx_1}{dt}=\lambda N_1,1\times 10^{5}=\lambda N_1 $

$ \frac{dx_2}{dt}=\lambda N_2,3.7\times 10^{10}=\lambda N_2 $

$ \frac{N_1}{N_2}=\frac{1\times 10^{5}}{3.7\times 10^{10}}=\frac{1\times {{10}^{-5}}}{3.7}=0.27\times {{10}^{-5}} $ .