$18\mathrm{.}31.$ Gaseous Diffusion of Uranium. $($a$)$ A process called

gaseous diffusion is often used to separate isotopes of uranium$-$

that is$,$ atoms of the elements that have different inasses, such as

${?}^{235}U$ and ${?}^{238}U.$ The only gaseous compound of uranium at ordinary

temperatures is uranium hexafluoride, $U{F}_6.$ Speculate on how

${?}^{235}U{F}_6$ and ${?}^{238}U{F}_6$ inolecules might be separated by diffusion.

$($b$)$ The molar masses for ${?}^{235}U{F}_6$ and ${?}^{238}U{F}_6$ molecules are

$0\mathrm{.}349k\frac{g}{m}ol$ and $0\mathrm{.}352k\frac{g}{i}$nol, respectively. If uranium hexaflu$-$

oride acts as an ideal gas, what is the ratio of the root$-$mean$-$

square speed of ${?}^{235}U{F}_6$ molecules to that of ${?}^{238}U{F}_6$ molecules if the

temperature is uniform?