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13. Nuclei — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics13. Nuclei1 Mark
MCQ
A radioactive sample at any instant has its disintegration rate $5000$ disintegration per minute. After $5$ minutes, the rate is $1250$ disintegrations per minute. Then, the decay constant (per minute) is
  • A
    $0.8 \, ln\, 2$
  • ✓
    $0.4 \, ln\,  2$
  • C
    $0.2 \, ln\,  2$
  • D
    $0.1 \, ln\,  2$
✓

Answer

Correct option: B.
$0.4 \, ln\,  2$
b
(b)$\lambda = \frac{{{{\log }_e}\frac{{{A_1}}}{{{A_2}}}}}{t}$

$= \frac{{{{\log }_e}\frac{{5000}}{{1250}}}}{5} = 0.4 \, ln\, 2$

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