Final answer:
The most stable cation among the given options is Mg2+.
Step-by-step explanation:
The most stable cation among the given options is Mg2+.
Stability of cations is determined by the charge-to-size ratio. As the charge of a cation increases, the size of the ion decreases. Smaller ions tend to have higher charge densities, leading to stronger ionic bonds and greater stability.
Among the given cations, Mg2+ has the highest charge-to-size ratio, making it the most stable.