2. Had chlorine been used instead of fluorine to form UCl₆, what differences would have been observed?
   
   
   1. The difference in effusion rates for the two uranium isotopes would be greater than 0.4%, so fewer filtering chambers (pores) would be needed to enrich the sample.
   2. The difference in effusion rates for the two uranium isotopes would be less than 0.4%, so fewer filtering chambers (pores) would be needed to enrich the sample.
   3. The difference in effusion rates for the two uranium isotopes would be greater than 0.4%, so more filtering chambers (pores) would be needed to enrich the sample.
   4. The difference in effusion rates for the two uranium isotopes would be less than 0.4%, so more filtering chambers (pores) would be needed to enrich the sample.