posted by 000 .
there are two naturally occurring isotopes of the element zinc. the relative abundance and mass of each are as follow
30zn=48.89% 63.929 amu
is it 0.4889(63.929)+027.81(65.926) divide by 2?
What else is in the naturally occuring zinc, the abundance of the two isotopes combined is only 76 percent (about) by adding 48.9+27.8 . Something else has to be there.
Dont divide by two, you will divide by 1.0 (the sum of the abundances, hopefully 100 precent or 1.0). But something is missing here.