Neet
Atoms And Nuclei
NEET 2022 Phase 2
MCQ+4 / -12022
At any instant, two elements X1 and X2 have same number of radioactive atoms. If the decay constant of X1 and X2 are 10 \(\lambda\) and \(\lambda\) respectively, then the time when the ratio of their atoms becomes \({1 \over e}\) respectively will be :