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At a given instant there are 25% undecayed radioactive nuclei in a sample. After 10 seconds the number of undecayed nuclei redu ces to 12.5%.

Calculate:

(i) mean life of the nuclei

(ii) the time in which the number of undecayed nuclei will further reduce to 6.25% of the reduced number.

#Physics #Modern physics

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7 Answers

1

Grandmaster ·2009-12-13 06:08:33

half life is 10 s therefore Î»=0.63/10 and hence mean life is 1/Î»

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1

Grandmaster ·2009-12-13 06:09:09

more 10 s it would take to reduce to 6.25%

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106

Asish Mahapatra ·2009-12-13 06:09:48

half life = 10 sec = 0.693/k

So, mean life = 1/k = 10/0.693 = 14.43 sec^-1

if i dont understand the language (see how poor my english is ) part 2 is 40 sec ??

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39

Dr.House ·2009-12-13 06:15:04

its `of` the reduced number,

sorry nowadays trying to learn fast typing :P

and asish , first part u have given the right answer

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39

Dr.House ·2009-12-13 06:20:33

am getting 20 seconds asish.

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62

Lokesh Verma ·2009-12-13 20:08:57

@Bhargav.. it is called "learn typing" :P not "learn fast typing" :D :P

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Avinava Datta ·2009-12-30 10:22:18

is the answer to the second part be 40 seconds??

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