Question Detail
Question
A radioactive element has a count rate of 600 Hz. If the half life of this element is 3 minutes, how many minutes will it takes for the count rate to diminish to 150 Hz?
Correct Answer
Option D is the correct answer.
Detailed Explanation
The count rate halves every half-life. 600 → 300 (one half-life, 3 min), 300 → 150 (two half-lives, 6 min). So it takes 6 minutes to go from 600 to 150 Hz.
Hint
Each half-life reduces the count rate by half.