Question
Question: In a sample of radioactive material, what percentage of the initial number of active nuclei will dec...
In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life?
A
37 %
B
50 %
C
63 %
D
69.3 %
Answer
63 %
Explanation
Solution
N = N0e–lt
Number of nuclei decayed = N0 – N
% of initial nuclei decayed= 
× 100
= 
×100
= (1–e–lt) × 100
= (1 – 0.37) × 100
= 63%