Two Radioactive substances decay |NUCLEARPHYSICSEEMain2019

JEE MAIN 2019

10-04-2019 S2

Question

Two radioactive substances $A$ and $B$ have decay constants $5 \lambda$ and $\lambda$ respectively. At $\mathrm{t}=0$, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $\left(\frac{1}{\mathrm{e}}\right)^2$ will be.

Select the correct option:

$\frac{1}{2 \lambda}$

$\frac{1}{4 \lambda}$

$\frac{1}{\lambda}$

$\frac{2}{\lambda}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution