The count rate from `100cm^(3)` of a radioactive liquid is `c`. Some of this liquid is now discarded. The count rate of the remaining liquid is found to be `c//10` after three half-lives. The volume of the remaining liquid, in `cm^(3)`, is

Options

A. 20
B. 40
C. 60
D. 80

Answer

D

Explanation

Initial count rate (CR) for `1 cm^3` of liquid =c/100
After 3 half-lives , CR for `1 cm^3` of liquid =`1/8xxc/100`
Let the volume of the remaining liquid=`V cm^3`
`therefore` CR of this liquid , `Vxxc/800 =c/10`. Or V=80.