Answer to Question #94646 in General Chemistry for Charisse

Question

Uranium-235 has a half life of 7.04×10^8 years. How many years will it take for 99.9% of a U-235 sample to decay?

Answer 1

1)     N(t) = N₀ * 2 ^–t/T1/2

2)     0.1 = 100 * 2 ^{–t/7.04*10^8}

3)     t = 7.016 * 10⁹