Uranium-235 Has a Half-Life of 7 $\times$ 10⁸ Years $\times$ 10⁵ Yr
B) 1

Uranium-235 has a half-life of 7.04 $\times$ 10⁸ years.How many years will it take for 99.9% of a U-235 sample to decay?

A) 7.0 $\times$ 10⁵ yr
B) 1.0 $\times$ 10⁶ yr
C) 4.7 $\times$ 10⁹ yr
D) 4.9 $\times$ 10⁹ yr
E) 7.0 $\times$ 10⁹ yr