Final answer:
To identify a stable atom with atomic mass number A=101, we need an isotope with an appropriate neutron-to-proton ratio for its atomic number and one that does not exceed Z>83 to be stable against beta decay, but exact isotope values cannot be determined without specific n/p ratios.
Step-by-step explanation:
To determine which atom with atomic mass number A=101 is stable to beta decay using the semiempirical mass formula, we must look at the neutron-to-proton ratio (n/p ratio).
Atoms with an n/p ratio that is too high are prone to beta decay, where a neutron is converted to a proton, thus increasing the atomic number (Z) while keeping the mass number (A) constant.
For stability against beta decay, the nuclide should have an n/p ratio close to the value that is considered stable for its particular atomic number range.
However, specific numbers aren't provided to conclusively identify which isotope of A=101 is stable. We are also informed that nuclides with Z>83 are typically unstable due to being too heavy, usually decaying by alpha emission, and that for light elements, a high neutron-to-proton ratio indicates beta decay would occur.
Therefore, we need to find an isotope of A=101 with the most appropriate n/p ratio for its Z that is not greater than 83.