TS EAMCET 06 May 2019 Shift 1 Solved Paper

Two radioactive materials R1 and R2 have decay constants 6 and respectively. The half life of R2 is 1.4 × 1017 s. Initially they contain some number of nuclei. The time at which the ratio of the remaining nuclei of R2 to that of R1 will be 'e' is: (Let In 2 = 0.7)