Final answer:
The true statement is A) Br-1 is smaller than Br; however, it should be noted that Br- is actually larger than neutral Br. The size of ions compared to their neutral atoms depends on their electron gain or loss.
Step-by-step explanation:
The correct statement from the options is A) Br-1 is smaller than Br. When an atom gains an electron, it becomes an anion which generally increases its radius due to increased electron-electron repulsion in the larger electron cloud. Conversely, an atom that loses electrons becomes a cation, and its radius decreases. Therefore, Br- has a larger radius than the neutral Br atom due to the gain of an additional electron.
Considering the other options, ions change size relative to their neutral atoms based on whether they gain or lose electrons. A cation like Al3+ loses three electrons, making it smaller than the neutral Al atom. Similarly, K+ is a cation and is thus smaller than its neutral counterpart. An anion like S2- gains two electrons, which makes it larger than the neutral sulfur (S) atom.