## Chemistry 12th Edition

$1\times10^8$ helium atoms
diameter of helium atom: $1\times10^2pm$ = $1\times10^{-10}m$ distance = 1 cm = $1\times10^{-2}m$ number of helium atoms = $\frac{1\times10^{-2}}{1\times10^{-10}}$ = $1\times10^8$ helium atoms