INTEGER ANSWER TYPE 3

In a uranium ore sample, the ratio of U238 to Pb206 nuclei is 1/3

Assuming that all the lead present in the ore is final stable product of U238

, find the age of the ore (in 109 year) if half life of U238 is 4.5 × 109 year.

9 Answers

1
ronak agarwal ·

is it 9 ??

1
ronak agarwal ·

sum1 plz tell me is it correct?????

62
Lokesh Verma ·

ronak the answer will depend on wheter the ratio is by mass or by moles..

that is not very clear..

but if the question is by moles, your answer is correct

4
UTTARA ·

yes ronak u're ans is correct but plzz can u post ure entire solution???

1
ronak agarwal ·

not a big solution.....

half life is 4.5 (in 109) years.....

and the ratio says that the sample will have 1/4th of the orginal uranium ore......

so after 4.5 it becomes 1/2 and after another 4.5 it becomes 1/2 of 1/2......that is 1/4th of original....

i hope the solution is clear.....

1
Manmay kumar Mohanty ·

But it has to 1/3rd not 1/4th.

29
govind ·

@manmay..
ronak is ryt it's 1/4

1
ronak agarwal ·

@ manmay

the ratio of uranium to lead is 1/3...that means for every 1 part of uranium there are three parts of lead....

so out of total of four parts uranium is only 1....

i hope this cleared ur confusion...

1
satyam ·

answer is 9 because it will take two half lifes for the ratio to become 1/3

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