Answer:
The Answer is 3.
Step-by-step explanation:
In the balanced redox equation Co + 3Ag⁺ → Co³⁺ + 3Ag, the number of electrons being exchanged can be determined by comparing the oxidation states of the elements involved in the reaction.
The oxidation state of cobalt (Co) increases from 0 to +3, indicating a loss of electrons. On the other hand, the oxidation state of silver (Ag) decreases from +1 to 0, indicating a gain of electrons.
Since each silver ion (Ag⁺) gains one electron and there are three silver ions involved, a total of 3 electrons are gained by silver. Similarly, since cobalt (Co) loses 3 electrons, the number of electrons exchanged is also 3.
Therefore, the correct answer is 3.