Question
A sample of radioactive substance has 10^{6} radioactive nuclei. Its halflife time is 20 seconds. How many nuclei will remain after 10 seconds?




None of these
medium
Solution
If in a sample of radioactive substance the initial number of nuclei be N_{0}, then the number of nuclei after n halflives is given by
The halflife of the radioactive substance is 20 seconds. The number of halflives in 10 seconds is
.
The initial number of nuclei is . Hence the number of nuclei left after halflife will be
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