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Standard XII

Chemistry

First Order Reaction

For a radioac...

Question

For a radioactive material, half life is 2 minutes. If initially, there are 1000 nuclei. Find the time taken so that 125 nuclei are remaining.

8 minutes

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16 minutes

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6 minutes

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4 minutes

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Solution

The correct option is C 6 minutes
After half life, number of nuclei remaining are half of initial.

So, after 1st half life number of nuclei remained are 500, after 2nd half life number of nuclei remained are 250, after 3rd half life number of nuclei remained are 125.

So, total time taken is of three half lives which is $3 \times 2 = 6$ minutes.

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