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Q.
The half-life of a radioactive sample is $5$ seconds. If the initial mass of the sample is $60$ grams then the time required to reduce the sample to $7.5$ grams is:
TS EAMCET 2020
Solution:
Decay scheme of given sample is as shown below
So, time required by sample to reduced to $7.5 g$ is
$\Delta t=3 \times T_{1 / 2}=3 \times 5=15 s$
