Suppose the percent abundance of the lighter isotope were 62%. Chlorine has two stable isotopes of mass 34.97 u and 36.97 u. Explain what would be the atomic mass of Cl when the actual abundance is 75.77%.
Suppose the average atomic mass from the periodic table was 79.06 u. Bromine occurs naturally as two isotopes, one with a mass of 78.918 u and the other with a mass of 80.916 u. Explain what would be the percent abundance of the lighter isotope?