A substance has half of 3 min. After 6 min, the count rat...
A substance has half of 3 min. After 6 min, the count rate was observed to be 400. What was its count rate at zero time?
1600
1200
200
2400
Correct answer is A
Let the count rate at zero time be N
N 3min→ N2 3min→ N4
N4
= 400
N = 400N/4 x N
= 1600
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