Question
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
✓
Answer
(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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