When is alpha particle emission most likely to occur?
a. when the nucleus has more than 83 protons.
b. when the ratio of neutrons to protons in the nucleus is too high to be stable. c. when the nucleus has a mass of more than 83 amu.
d. when the ratio of neutrons to protons in the nucleus is not exactly balanced.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.