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Radio active phosphorus 32 has a half li...

Radio active phosphorus `32` has a half life of `14` days. A source containing this isotope has an initial activity of 10 m Ci.
(i) What is the activity of the source after 42 days?
(ii) What time elapses before the activity of the source falls to 2.5 mCi?

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The correct Answer is:
[(i) 1.25 mCi (ii) 28 days]
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