InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
At a given instant there are 25% undecayed radioactive nuclei in a sample. After 10 s the number of undecayed nuclei reduces to 12.5%. Calculate (a) mean life of the nuclei, (b) the time in which the number of undecayed nuclei will further reduce to 6.25% of the reduced number. |
|
Answer» Correct Answer - A::C::D (a) In 10 s, number of nuclei has been reduced to half (25% to 12.5%). Therefore, its half-life is `t_(1//2) = 10`s Relation between half-life and mean life is `t_(mean)=(t_(1//2))/(1n2)=10/0.693s` `t_(m ean)=14.43s` (b) From initial 100% to reduction till 6.25%, it takes four half-lives. `100%overset(t_(1//2))rarr50%overset(t_(1//2))rarr25%overset(t_(1//2))rarr12.5%overset(t_(1//2))rarr6.25%` `t=4t_(1//2)=4(10)s=40s` `t=40s` |
|