Latest L&T Aptitude Question SOLUTION: 16 grams of radioactive material decays in 10 years. How long will it take to decay to 1 gram?

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16 grams of radioactive material decays in 10 years. How long will it take to decay to 1 gram?

Asked In L&T PUJA PRASAD (9 years ago)

Unsolved Read Solution (6)

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Read Solution (6) :

Krishna Vinci  (9 years ago)

every radio active element decays to half of its weight evry time.. whenever bombarded.
so, it decays into 16-> 8-> 4->2->1
Totally it takes 40 years to decay to 1gram.

Is this solution Helpfull? Yes (15) | No (2)  

jyotsna kumari  (9 years ago)

16gm in 10 yr
.
. . 1gm in 10/16=.625

Is this solution Helpfull? Yes (7) | No (7)  

ravi ranjan  (9 years ago)

i think 10 years

Is this solution Helpfull? Yes (3) | No (6)  

Anna  (9 years ago)

16 gm reduced to 8gm in 10yrs
so 8 gm get decayed
for decaying 1 gm it takes 10/8 yrs
for decaying 8 gm it takes 10/8*8

remaining 8 gm
need to decay 7 to get 1 gm remaining
for decaying 7 it takes
10/8*8*7
=10*7
=70 years

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veena  (8 years ago)

16 gm reduced to 8gm in 10yrs. So 8 gm get decayed.
For decaying 1 gm it takes 10/8 years. For decaying 8 gm it takes 10/8*8
Remaining 8 gm need to decay 7 to get 1 gm remaining.
For decaying 7 gm it will take
10/8*8*7 = 10*7 = 70 years

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vikrant  (8 years ago)

decay of radioactive material is given by n(t)=n(t0)*exp^(-At)... after 10 years of decay the substance will not reduce to exactly 0 (it will tend to 0). i considered it to be .001 gm then calculated A by taking ln of both the sides and then solved problem for 1 gm it comes out to be 7.135 years.

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