The half lives of a radioactive sample are 30 years and 60 years from `alpha`- emission and `beta`- emission respectively If the sample decays both by

Question

The half lives of a radioactive sample are 30 years and 60 years from `alpha`- emission and `beta`- emission respectively If the sample decays both by

The half lives of a radioactive sample are 30 years and 60 years from `alpha`- emission and `beta`- emission respectively If the sample decays both by alpha-emission and `beta`-emission simultaneously, the time after which, only one-fourth of the sample remain is
A. 10 years
B. 20 years
C. 40 years
D. 45 years

Monjur Alahi

4 views

2025-01-04 04:42

1 Answers

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Salim Ahmed Kawsar · Accepted Answer · 2023-02-05T15:29:48+06:00

Salim Ahmed Kawsar

Correct Answer - C
`lambda_(1)=1/30`
`lambda_(2)=1/60`
`lambda=lambda_(1)+lambda_(2)`
`lambda=1/20`
`N=(N_(0))/(2^(t)//t^(1//2))`
`N_(0)/4 = (N_(0))/((2)^(t//t^(1//2)))`
`:. t=2t_(1//2)=2xx(0.693)/lambda`
`t=2xx0.693xx20yrs`
`=27.72yrs`

4 views Answered 2023-02-05 15:29