Final answer:
The most likely ion to form an insoluble sulfate is the calcium ion (Ca²+). Insoluble sulfates include those of alkali metals, ammonia, and heavy alkaline earth metal ions such as calcium, barium, and strontium.
Step-by-step explanation:
The most likely ion to form an insoluble sulfate is the calcium ion (Ca²+). Insoluble sulfates include those of alkali metals, ammonia, and heavy alkaline earth metal ions such as calcium, barium, and strontium. Since calcium is one of the heavy alkaline earth metals, its sulfate (CaSO₄) is insoluble.
The most likely ion to form an insoluble sulfate is the calcium ion (Ca²+). Insoluble sulfates include those of alkali metals, ammonia, and heavy alkaline earth metal ions such as calcium, barium, and strontium.