Calculate the relative rates of diffusion for ${}^{235}\mathrm{UF}_6 \mathrm{and} {}^{238}\mathrm{UF}_6$

According to Graham’s law

$\mathrm{r} \mathrm{\alpha } \frac{1}{\sqrt{\mathrm{M}}}$

Then the rate of diffusion is $\frac{{\mathrm{r}}_1}{{\mathrm{r}}_2}=\sqrt{\frac{M_2}{M_1}}$

$\frac{{\mathrm{r}}_{{235}_{{\mathrm{UF}}_6}}}{{\mathrm{r}}_{{238}_{{\mathrm{UF}}_6}}}=\sqrt{\frac{238}{235}}=1.006$