Half-lives of two radioactive substances `A` and `B` are respectively `20` minutes and `40` minutes. Initially, he sample of `A` and `B` have equal number of nuclei. After `80` minutes the ratio of the remaining number of `A` and `B` nuclei is :

Options

A. `1:16`
B. `4:1`
C. `1:4`
D. `1:1`

Answer

C

Explanation

Number half lives For A= 4
For B= 2
`therefore (N_(A))/(N_(B))= (2^(n_(B)))/(2^(n_(A))) = (2^(2))/(2^(4)) = (1)/(4)`