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?
Take Free Practice Test On 2026 JAMB UTME, Post UTME, WAEC SSCE, GCE, NECO SSCE
Correct Answer: Option A
Explanation:
Let the count rate at zero time be N
N \(\frac{3 min}{\to}\) \(\frac{N}{2}\) \(\frac{3 min}{\to}\) \(\frac{N}{4}\)
\(\frac{N}{4}\)
= 400
N = \(\frac{400}{N/4}\) x N
= 1600
Let the count rate at zero time be N
N \(\frac{3 min}{\to}\) \(\frac{N}{2}\) \(\frac{3 min}{\to}\) \(\frac{N}{4}\)
\(\frac{N}{4}\)
= 400
N = \(\frac{400}{N/4}\) x N
= 1600