• # question_answer Compare the rates of diffusion of $^{235}U{{F}_{6}}$and$^{238}U{{F}_{6}}$.

Molecular mass of $^{235}U{{F}_{6}}=235+6\times 19=349$ Molecular mass of $^{238}U{{F}_{6}}=238\,+6\times 19=352$ $\therefore$ $\,\frac{{{r}_{1}}{{(}^{235}}U{{F}_{6}})}{{{r}_{2}}{{(}^{238}}U{{F}_{6}})}=\sqrt{\frac{{{M}_{2}}}{{{M}_{1}}}}\,=\sqrt{\frac{352}{349}}\,=1\cdot 004$ Thus, $r{{(}^{235}}U{{F}_{6}}):r\,{{(}^{238}}U{{F}_{6}})=1\cdot 004:1$.