Nuclear Physics And Radioactivity Question 448

Question: One gram of a radioactive sample of half-life 10 min is sealed in a capsule at time t=0. Amount of sample decayed up to 5 min is

Options:

A) 0.293g

B) 0.5g

C) 0.25g

D) 0.707g

Show Answer

Answer:

Correct Answer: A

Solution:

[a] Use the relation $ N=N_{0}{{e}^{-\lambda t}} $ where the decay constant $ \lambda =(0.693/T_{half}). $ The half-life period $ T_{half} $ is given to be 10min. The amount N of radioactive sample remaining at the end of 5 min comes out to be about $ 0.707g, $ so that the amount of sample decayed is $ (1-0.707)=0.293g. $