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A Geiger melter countries is used to stu...

A Geiger melter countries is used to study , the radicuacting process in the abserence of radoactive substance A , it couts `2` disingration per second (dps) Al the start in due presence of A, it recoirds `23` dps and after `10` in 3 dps,
(i) What does it count after `20` min?
(ii) What is the half -life A?

A

`8 dps, 10 mi n`

B

`5 dps, 10 mi n`

C

`5 dps, 20 mi n`

D

`5 dps, 5 mi n`

Text Solution

Verified by Experts

The correct Answer is:
A
In the absence of `A,3 dps` is zero error, hence Initial count`=23-3=20 dps`
After `10 min= 13-3=10 dps`
After `20 min= 5 dps` ( recorded `=5+3=8 dps)`
(`50%` fall in `10 min, T_(50)=10min)`
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