The half life of a radioactive nuclide i

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Target Exam

CUET

Subject

Physics

Chapter

Nuclei

Question:

The half life of a radioactive nuclide is 20 hours. What fraction of original activity will remain after 80 hours?

Options:

$\frac{1}{8}$

$\frac{1}{16}$

$\frac{1}{4}$

$\frac{1}{32}$

Correct Answer:

$\frac{1}{16}$

Explanation:

$N = \frac{N_0}{2^n}$

$n = \frac{t}{t_\frac{1}{2}} = \frac{80}{20} = 4$

$N = \frac{N_0}{2^4} = \frac{N_0}{16}$

The correct answer is Option (2) → $\frac{1}{16}$