Question
Question: 90 % of a radioactive sample is left undecayed after time t has elapsed. what percentage of the init...
90 % of a radioactive sample is left undecayed after time t has elapsed. what percentage of the initial sample will decay in a total time 2t. –
A
20 %
B
19 %
C
40 %
D
38 %
Answer
19 %
Explanation
Solution
N = N0 (0.9)2
N = 0.81 N0
81% of initial value is left hence % of the initial sample decayed
= 100 – 81 = 19 %