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A sample of radioactive element has a ma...

A sample of radioactive element has a mass of `10 g` at an instant `t=0`. The approximate mass of this element in the sample after two mean lives is

A

2.50 g

B

3.70 g

C

6.30 g

D

1.35 g

Text Solution

Verified by Experts

The correct Answer is:
D
`N= N_(0) e^(- lamda t) rArr M = M_(0) e^(-lamda t)`
`t= (2)/(lamda) = 2tau`
`therefore M= 10 e^(-lamda ((2)/(lamda)))= 10 ((1)/(e))^(2) rArr M= 1.35g`
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