If 8g of a radioactive substance decays into 0.5 g in 1 h, then the half-life of the substance is

Options

A. 45 min
B. 10 min
C. 15 min
D. 30 min

Answer

C

Explanation

`N_(0)=8` gm, `N=0.5` gm, `t=1` hr, `T=?`
`N/N_(0) =(1/2)^(n)`
`0.5/8=(1/2)^(n)`
`5/80=(1/2)^(n)`
`1/16 =(1/2)^(n)`
`(1/2)^(4)=(1/2)^(n)`
`:. n=4`
`t/T=4`
`T=t/4=1/4=60/4=15` min