Final answer:
In the given reaction, 3 electrons are transferred.
Step-by-step explanation:
The given reaction is: 2 Ir³+(aq) + 3 Zn(s) → 3 Zn²+(aq) + 2 Ir(s).
In this reaction, 3 electrons are transferred.
The oxidation state of iridium changes from +3 to 0, so it gains 3 electrons. At the same time, zinc changes from 0 to +2, so it loses 2 electrons. Therefore, a total of 3 electrons are transferred in this reaction.