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

Question

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

TestHub · Accepted Answer

No. of half lives n 1 ​ = 20 80 ​ = 4 ; ​ n 2 ​ = 40 80 ​ = 2 N 0 A ​ N 1 ​ ​ = ( 2 1 ​ ) n 1 ​ = ( 2 1 ​ ) 4 = 16 1 ​ ⇒ for A N 0 B ​ N 2 ​ ​ = ( 2 1 ​ ) n 2 ​ = ( 2 1 ​ ) 2 = 4 1 ​ ⇒ for B N 2 ​ N 1 ​ ​ = 16 1 ​ × 1 4 ​ = 4 1 ​ ( ∵ N 0 A ​ = N 0 B ​ ) ​

Physics - Modern Physics Question with Solution | TestHub

Options:

Doubts & Discussion