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A radioactive sample has `6.0 xx 10^18` active nuclei at a certain instant. How many of these nuclei will still be in the same active state after two half-lives?A. `1.5 xx 10^(18)`B. `3 xx 10^(18)`C. `6 xx 10^(18)`D. None of these |
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Answer» Correct Answer - A In one half-life the number of active nuclei reduces to half to original number. Thus in two half lives the number is reduced to `((1)/(2))xx((1)/(2))` of the original number. The number of remaining active nuclei is therefore. `6.0 xx 10^(18) xx ((1)/(2))xx((1)/(2)) = 1.5 xx 10^(18)`. |
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