## Chemistry and Chemical Reactivity (9th Edition)

$2.656\times10^{-23} g$
Since $1\ u = 1.66054\times10^{-24}\ g$: The mass of $^{16}O$ in g is $15.995\ u \times 1.66054\times10^{-24} g/u = 2.6560\times10^{-23} g$