The `t_(0*5)` of a radioactive substance is 100 days. After 400 days , one gram of element will be reduced to

Options

A. `0*5` g
B. `0*25` g
C. `0*125` g
D. `0*625` g

Answer

D

Explanation

Amount of substance left `=((1)/(2))^(n) xx` original amount
n(no. of half lives)=`("total time")/(t_(0.5))`
`=(400)/(100)=4`
Amount of substance left
`=((1)/(2))^(4) xx 1g =(1)/(16)xx 1 =0.0625 g`