posted by NEED HELP .
Copper has two naturally occurring isotopes. Cu-63 has a mass of 62.939 amu and relative abundance of 69.17%. Use the atomic weight of copper to determine the mass of the other copper isotope.
fraction*mass + fraction*mass = atomic mass Cu.
You know fraction and mass of one isotope. Th fraction of the second isotope is 1.00-fraction of first, and the periodic table gives you the atomic mass Cu. Solve for mass of second.
Is this for webassign? Cause I had that exact same problem lol does all of the USA use webassign?
well, I live in Indiana, West Lafayette and I am not sure all of the USA use webassign, and yes this is webassign