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Uranium- 238 decays to thorium-234 with ...

Uranium- `238` decays to thorium-`234` with half-life `5xx10^(9) yr`. The resulting nucleus is in the excited state and hence further emits `gamma`-rays to come to the ground state. It emits `20 gamma`-rays per second. The emission rate will drop to `5 gamma`-rays per second in

A

`1.25xx10^(9) yr`

B

`10^(10)yr`

C

`10^(-8)yr`

D

`1.25xx10^(-9)s`

Text Solution

Verified by Experts

The correct Answer is:
B
`t=2` half lifes, `t= nT=2xx5xx10^(9)` year
`10^(10)` year
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