CAPE Physics Unit 2 · 2017 · Paper 1 · Question Q44

What is the half-life for a radioactive isotope containing 10^{20} atoms with a decay constant of 1.60 \times 10^{-5}\text{ s}^{-1}?

1. (A)1.20 \times 10^{-19}\text{ hours}
2. (B)4.33 \times 10^{-16}\text{ hours}
3. (C)12.0 \times 10^0\text{ hours}
4. (D)4.33 \times 10^4\text{ hours}