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Two radioactive samples of different ele...

Two radioactive samples of different elements (half-lives `t_1` and `t_2` respectively) have same number of nuclei at `t=0`. The time after which their activities are same is

A

`(t_(1)t_(2))/(0.693(t_(2)-t_(1)))`

B

`(t_(1)t_(2))/(0.993)ln(t_(2))/(t_(1))`

C

`(t_(1)t_(2))/(0.693(t_(1)-t_(2)))`

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
A
`N_(1)=N_(1)e^(-lambda_(1)t),A_(1)=N_(1) lambda_(1) & N_(2)=N_(1)e^(-lambda_(2)t), A_(2)=N_(1)lambda_(2)`
In is given after time 't', `N_(2)=N_(1)`. Solving the above equations, we get time 't'.
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