Isotopes differ in the number of .
lone pairs
covalent bonds
neutrons
electrons
protons
The average molecular weight for element X is 59.97 g/mol. There are two known isotopes of element X, one weighing 59 g/mol, and the other weighing 61 g/mol. What is the relative abundance of each?
48.5% X-59, 51.5% X-61
50% X-59, 50% X-61
75% X-59, 25% X-61
51.5% X-59, 48.5% X-61
63% X-59, 37% X-61