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Physics · 2019
JEE Main · 9 January 2019, Shift 1 · Q28
A sample of radioactive material A, that has an activity of 10 mCi (1 Ci =3.7 × 10^10. decays/s), has twice the number of nuclei as another sample of…
A sample of radioactive material A, that has an activity of $\displaystyle 10 \mathrm{mCi}\left(1 \mathrm{Ci}=3.7 \times 10^{10}\right.$ decays/s), has twice the number of nuclei as another sample of a different radioactive material B which has an activity of $\displaystyle 20$ mCi. The correct choices for half-lives of A and B would then be respectively :
Official answer
(2)
$\displaystyle 20$ days and $\displaystyle 5$ days
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JEE Main 2019 Physics question, with the answer from NTA’s final answer key. Where our answers come from.