AIIMS2019Physics-Radioactivity

AIIMS 2019 Physics Half-life MCQ Question

Type: MCQ-numerical-Medium-Class 12

The decay rate is given as, N = N₀(1/2)ⁿ. The number of half lives is calculated as, 2ⁿ = 100. n lies between the 6 and 7. So, the radioactive element will decay between 6 and 7 half lives.

A

6

B

7

C

6.5

D

6.7

Correct Answer

Option A

Detailed Explanation

The equation 2n=1002^n = 100 implies that nn represents the number of half-lives, and solving for nn gives n6.64n \approx 6.64, which lies between 6 and 7. Therefore, the radioactive element will decay between 6 and 7 half-lives, making option A (6) the most accurate representation of the lower bound. Options B (7) and C (6.5) are incorrect as they do not accurately reflect the calculated range, while option D (6.7) is also not precise enough to represent the lower limit of the decay range.

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