## Chemistry (4th Edition)

There are $9.97 \times 10^{-15}$ moles of $Co$ in 6 billion atoms of $Co$.
Using Avogadro's number, we find: $6.00 \times 10^9 atoms \times \frac{1 mole}{6.022 \times 10^{23} atoms} = 9.97 \times 10^{-15}$ moles.