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>>Nuclei
>>First Order Radioactive Decay
>> $A human body excretes certain material b$

Question

A human body excretes certain material by a law similar to radioactivity. The body excretes half the amount injected in $24$ $h$ . Find the time in which activity falls to $3 μ$ $C i$ . If a person is injected technitium ( $t_{1 / 2}$ = $6 h$ ) and its activity just after the injection is $6 μ$ $C i$

A

$4.8$ $h$

B

$6$ $h$

C

$6.3$ $h$

D

none of these

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Updated on : 2022-09-05

Solution

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Correct option is A)

$\frac{1}{t}$ $= \frac{1}{t _{1}} + \frac{1}{t _{2}}$

$t$ $= \frac{t _{1} t _{2}}{t _{2} + t _{2}}$

$= \frac{2 4 \times 6}{2 4 + 6}$ $= 4.8$ $h$

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