TS EAMCET 9 May 2024 Shift 1 Solved Paper

As we know,
n=‌

log(‌ remaining fraction ‌

log(0.5)

)
For 28% decay ( 72% remaining)
n28=‌

log(0.72)

log(0.5)

≈0.473
For 82\% decay ( 18% remaining)
n82=‌

log(0.18)

log(0.5)

≈2.473
Time gap between 28% and 82% decay is the difference in the number of half lives,
‌ Time gap ‌‌=(n82−n28)×12min
‌=(2.473−0.473)×12
‌=2×12=24min
Therefore, time gap between 28% decay and 82% of radioactive substance is approximately 24 min.