Final answer:
Among the options given, Al⁺³ has the greatest charge density because it has a high charge of +3 on a relatively small ion. The correct option is (c) Al⁺³.
Step-by-step explanation:
The question concerns determining which of the given anions or cations has the greatest charge density. Charge density is defined as the charge over the volume of the particle. In this context, smaller ions with higher charges will generally have higher charge densities.
Considering the given options:
- (a) Br⁻¹
- (b) Ga⁺³
- (c) Al⁺³
- (d) I⁻¹
Both Ga⁺³ and Al⁺³ have a +3 charge, but Ga⁺³ is larger than Al⁺³ because gallium is lower on the periodic table. Hence, Al⁺³, being smaller, has a higher charge density. Therefore, the correct option is (c) Al⁺³.