A) 1/3
B) 1/4
C) 3
D) 2
Correct Answer: A
Solution :
Let N denote the total no of nuclei. Initially \[N={{N}_{u}}+{{N}_{s}}.\] After a time T since the activity decreased to one third, number of unstable nuclei will also become one third. So after a time T, \[N/2={{N}_{u}}/3+{{N}_{s}}.\] Solving the two equations we get \[{{N}_{s}}/{{N}_{u}}=1/3.\]You need to login to perform this action.
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