Half life of a radioactive substance is 6 minute. If its initial amount is 32g, then amount present after 18 minute is

Options

A. 4 g
B. 8 g
C. 16 g
D. 2 g

Answer

A

Explanation

`t_(1//2)=6min, N_(0)=32g`
Total time = 18 min
`(N)/(N_(0))=((1)/(2))^(n),:.n=("Total time")/("Half time")=(18)/(6)=3`
`:. (N)/(32)=((1)/(2))^(3)or(N)/(32)=(1)/(8)or N=(32)/(8)=4g`.