Final answer:
The ion that represents an element from group 1A on the periodic table is Z⁺, referring to a cation with a +1 charge.
Step-by-step explanation:
The ion that represents an element from group 1A (also known as group 1) on the periodic table would be Z⁺. Elements in group 1A are the alkali metals, and they characteristically have a single valence electron which they tend to lose, resulting in a cation with a +1 charge. This matches option a) Z⁺. In contrast, a group 1A ion would not have a 2+ or 3+ charge, nor would it gain electrons to become negatively charged since these elements are highly reactive and readily lose their single valence electron.
Understanding the ionization behavior of elements in different groups helps to predict the charge on ions formed during chemical reactions, contributing to the overall understanding of the periodic table and elemental properties.