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A radiacative moterial docays by simulat...

A radiacative moterial docays by simulataneous emission of two particle from the with respective half - lives `1620` and `810` year . The time , in year , after which one - fourth of the material remins is

A

`1080`

B

`2430`

C

`3240`

D

`4860`

Text Solution

Verified by Experts

The correct Answer is:
A

`(-dN)/(dt) = lambda_(1) N + lambda_(2) N `
`rArr log_(e) (N)/(N_(0)) = - (lambda_(1) + (lambda_(1)(lambda_(2))t`
when `N_(0) `is intial number of atoms
`Here lambda_(1) = (0.693)/(1620)` and `lambda_(2) = (0.693)/(810)`
`(N)/(N_(0)) = (1)/(4) rArr log _(e) (1)/(4) = -((0.693 )/(1620) +(03.693)/(810)) t`
`rArr t = 1.1080` year
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