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JEE Main 2023 (29 Jan, Shift 1) · Law of Radioactive Decay

Law of Radioactive Decay question from JEE Main 2023 (29 Jan, Shift 1)

Q31JEE Main 2023 · 29 JAN · SHIFT 1Easy

Law of Radioactive Decay

If a radioactive element having half-life of $30\text{ min}$ is undergoing beta decay, the fraction of radioactive element remains undecayed after $90\text{ min}$ . will be

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Answer: (c)

$n = \frac{90}{30} = 3$ half-lives.
Undecayed fraction $= \left(\frac{1}{2}\right)^3 = \frac{1}{8}$ .
So the answer is (c) $\frac{1}{8}$ .

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