Zinc has three major and two minor isotopes. for this problem, assume that the only isotopes of zinc are the major ones, zinc-64, zinc-66, and zinc-68. the atomic mass of zinc-64 is 63.9291 da, that of zinc-66 is 65.9260 da, and that of zinc-68 is 67.9248 da. calculate the atomic mass of zinc from the relative peak intensities in the following spectrum. peak intensity for zinc 64 = 100 peak intensity for zinc 66 = 57.4 peak intensity for zinc 68 = 38.6