If one mole of carbon atoms weight $12$ grams, what is the mass (in $grams$) of $1$ atom of carbon?

1 mole of $C=6.022\times {10}^{23}$ C atoms

Since mass of $6.022\times {10}^{23}$ C atoms=$12g$

Since mass of $1$ C atom=$\frac{12}{6.022\times 1023}=2\times {10}^{-23}$g