question_answer

Half lives of two radioactive nuclei A and B are 10 minutes and 20 minutes, respectively. If, initially a sample has equal number of nuclei, then after 60 minutes, the ratio of decayed numbers of nuclei A and B will be : [JEE Main 12-4-2019 Afternoon]

A) 9 : 8

B) 1 : 8

C) 8 : 1

D) 3 : 8

Correct Answer: A

Solution :

[a]

Number of nuclei decayed

Number of nuclei decayed

Since

Ratio of decayed numbers of nuclei