Physics · 2019
JEE Main · 10 April 2019, Shift 2 · Q26
Two radioactive substances A and B have decay constants 5 λ and λ respectively. At t =0, a sample has the same number of the two nuclei. The time…
Two radioactive substances A and B have decay constants $\displaystyle 5 \lambda$ and $\displaystyle \lambda$ respectively. At $\displaystyle \mathrm{t}=0$, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $\displaystyle \left(\frac{1}{\mathrm{e}}\right)^2$ will be:
Official answer
(3)
$\displaystyle 1 / 2 \lambda$
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JEE Main 2019 Physics question, with the answer from NTA’s final answer key. Where our answers come from.