SSC
PHYSICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The half-life of Radon-222 is 4 days. If the initial mass of radon is 20g, what is the mass decayed after 12 days?
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2.5g
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17.5 g
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15.0g
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5.0g
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Explanation:
Detailed explanation-1: -15.2 days is 4 HALF LIVES. A bit over 6⋅g of 222Rn will remain.
Detailed explanation-2: -and =ln2t12. The half life is t12=3.82. N0=4.38g. =ln23.82=0.1815d−1. N(15.2d)=4.38⋅e−0.1815⋅15.2. =0.278g. 21-Dec-2016
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