Question

12.5% of an isotope remains after 8 years from the initial stage. After 8 more years the quantity persent will be?

Answer 1

@shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg @shubhamsrg

Answer 2

12.5 % = 3 half lives = 8 years
=>1 half life = 8/3 years
after 8 more years, that is 16 years,
no. of half lives = 16 /(8/3) = 6
does it help ?

Answer 3

was i clear ?

Answer 4

No!!

Answer 5

I can't understand

Answer 6

@shubhamsrg

Answer 7

okay,,leme try,,you know the meaning of half life ?

Answer 8

No..... i think..half its date of expiry

Answer 9

half life means the time object takes to reduce to half its initial value
eg. suppose we had 200 g of something
now after 1 half life, it reduces to 200/2 i.e. 100 gm
after another half life, it gets 100/2 i.e 50 gms and so on..

Answer 10

are you getting it ?

Answer 11

Yup

Answer 12

now,,in your ques,,if initial value was 100gm, can you tell me after how many half lives will it get to 12.5 gm ?

Answer 13

3

Answer 14

and how many half lives for 25 gm ?

Answer 15

2

Answer 16

alright,,seems you're comfortable with it ..
now,,
it took 3 half lives in 8 years
which means in 1 year => 3/8 half lives
you are asked about 16 years,,so that'll be 6 half lives..cool till now ?

Answer 17

ok

Answer 18

then..

Answer 19

quantity persent will be?

Answer 20

see,,after every half lives,,quantity gets 1/2..
if initial was n
after 1 half life,, -->n/2 --> then n/4 -->n/8 ........
thus for 6 half lives ,, it must be n/(2^6)
here n=100 ..
was i clear?

Answer 21

Yes....but n=100 hw

Answer 22

we assumed it to be 100 gm initially,,according to which we had 12.5 gms after 3 half lives..

Answer 23

since all was in %

Answer 24

so 12.5/2^3

Answer 25

=1.5 Yup....thxxx a lot brother

Answer 26

wonderful teacher.....)))

Answer 27

1.56 approx..

Answer 28

lol..nevermind! :P