3 carbons and 8<span> hydrogens = </span>11 atoms<span> in propane </span>per molecule
<span>2.12 mol C3H8
</span>6.02<span> x </span>1023<span> molecules of C3H8
</span>
11 atoms
The mass numbers of the different isotopes of that element are averaged according to their respective abundances in nature.
