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20% of a radio active element disintergr...

`20%` of a radio active element disintergrates in `1` hr. The percentage of the radio active element disintergrated in `2` hrs will be

A

`36%`

B

`64%`

C

`60%`

D

`40%`

Text Solution

Verified by Experts

The correct Answer is:
A
`W=(W_(0))/(2^(n))`. Intial amount `W_(0)` after one hour amount of remaining sample `=80%W_(0) , W_(1)=(80)/(100)W_(0)`
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