1.

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

Answer» Correct Answer - C
`(N_(A))/(N_(B)) = (N_(0)((1)/(2))^(80//20))/(N_(0)((1)/(2))^(80//40)) =(((1)/(2))^(4))/(((1)/(2))^(2))=((1)/(2))^(2) = (1)/(4)`


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