Chemistry

Problem

Which expression correctly gives the number of undecayed nuclei

N

left after

n

half-lives when the initial number is

N_0

? a)

N = N_0\,2^{n}

N = \dfrac{N_0}{2^{n}}

N = N_0\,e^{-n}

N = N_0\,2^{-\tfrac{n}{2}}