We separate U-235 from U-238 by fluorinating a sample of uranium to form UF₆ (which is a gas) and then taking advantage of the different rates of effusion and diffusion for compounds containing the two isotopes. Calculate the ratio of effusion rates for ²³⁸UF6 and ²³⁵UF₆. The atomic mass of U-235 is 235.054 amu and that of U-238 is 238.051 amu.