After 2 hr the radioactive substance becomes 1/16 th of original amount. The `t_(1//2)` in minutes is

Options

A. 60 min
B. 120 min
C. 30 minutes
D. 15 minutes

Answer

C

Explanation

`t=2 hrs = 2xx60 =120` min
`(N)/(N_(0))=(1)/(16), t_(1//2)=?`
`N=(N_(0))/(2^(n)) implies " "(N)/(N_(0))=(1)/(2^(n))`
`implies (1)/(16)=(1)/(2^(n)) implies " "n=4`
`n=(t)/(t_(1//2))implies t_(1//2)=(t)/(n)=(120 "min")/(4)`=30 min