Three isobars of mass number A = 64 have measured neutral atomic masses: for Z = 28, M = 63.9300 u; for Z = 29, M = 63.9270 u; and for Z = 30, M = 63.9290 u. Using the mass-parabola idea for isobars, which statements are consistent with the data?
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Question

Three isobars of mass number A = 64 have measured neutral atomic masses: for Z = 28, M = 63.9300 u; for Z = 29, M = 63.9270 u; and for Z = 30, M = 63.9290 u. Using the mass-parabola idea for isobars, which statements are consistent with the data?

Select all that apply

G1 Physics · Accepted Answer

For fixed mass number A, nuclear stability among isobars is associated with the minimum of the atomic-mass parabola. The measured masses are: Z=28: 63.9300 u, Z=29: 63.9270 u, Z=30: 63.9290 u. The Z=29 isobar has the lowest mass, so A is correct. The Z=28 isobar is neutron-richer than Z=29 and has greater mass. A β⁻-decay increases Z by 1 and can move it toward the lower-mass isobar. Thus B is correct. The Z=30 isobar is proton-richer than Z=29. β⁺-decay or electron capture decreases Z by 1 and…