Question

# Let's take a hypothetical radioactive nuclide sample of 80X. It weighs 80 gm. Find the number of active nuclei remaining after a time of 0.5 second. Given its decay constant is 2 s−1 x e

Solution

## The correct option is A Let's see what all is given to us. Nuclide sample of 80X weighing 80 gm. Time elapsed 0.5 sec Decay constant λ = 2s−1  What is being asked is the number of active nuclei left after given time duration. N=N0 e−λt I dunno N0 . Can I find N0 from what is given.   Yes!!! 80 gm of 80X nuclide Means a mole of it. Means the sample has 6.023×1023  Nucleus to begin with. Let's put things together. N=6.023×1023×e−0.5×2N=6.023×1023/e

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