8 grams of a radioactive substance is reduced to 0.5 g after 1 hour . The `t_(1//2)` of the radioactive substance is

Options

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

Answer

A

Explanation

Amount of substance left
`=((1)/(2))^(n)xx` original amount
`=03.5 g =[(1)/(2)]^(n)xx8 g`
`[(1)/(2)]^(n)=(0.5)/(8)=(1)/(16)=[(1)/(2)]^(4)`
n=4
No. of half lifes =4
Total time =1 hour
So half life time =15 minutes .