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A sample of radioactive substance loses ...

A sample of radioactive substance loses half of its activity in 4 days. The time in which its activity is reduced to 5% is

A

(a) 12 days

B

(b) 8.3 days

C

(c) 17.3 days

D

(d) None of these

Text Solution

Verified by Experts

The correct Answer is:
C
`lambda=(1n2)/(t_(1//2)) = (1n2)/(4) day^-1`
Now, apply
`R=R_0e^(-lambdat) implies 5=100e^(-lambdat)`
Substituting value of `lambda`, we can find t.
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